Patch taken from Nix:
   https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/libraries/qt-5/5.11/qtwebkit.patch

diff --git a/Source/WebKit2/PlatformQt.cmake b/Source/WebKit2/PlatformQt.cmake
--- a/Source/WebKit2/PlatformQt.cmake
+++ b/Source/WebKit2/PlatformQt.cmake
@@ -261,6 +261,7 @@
 list(APPEND WebKit2_SYSTEM_INCLUDE_DIRECTORIES
     ${GLIB_INCLUDE_DIRS}
     ${GSTREAMER_INCLUDE_DIRS}
+    ${GSTREAMER_PBUTILS_INCLUDE_DIRS}
     ${Qt5Quick_INCLUDE_DIRS}
     ${Qt5Quick_PRIVATE_INCLUDE_DIRS}
     ${SQLITE_INCLUDE_DIR}

'>guix</a></td><td class='form'><form method='get'>
<input type='hidden' name='id' value='bd19671f8a500f7bd5d17f8d08e4119a774acb46'/><select name='h' onchange='this.form.submit();'>
<option value='koszko' selected='selected'>koszko</option>
<option value='koszko-scripts'>koszko-scripts</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>refs</a><a class='active' href='/guix/log/gnu/packages/rdf.scm'>log</a><a href='/guix/tree/gnu/packages/rdf.scm?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>tree</a><a href='/guix/commit/gnu/packages/rdf.scm?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>commit</a><a href='/guix/diff/gnu/packages/rdf.scm?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/rdf.scm'>
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<input class='txt' type='search' size='10' name='q' value=''/>
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<div class='path'>path: <a href='/guix/log/?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>root</a>/<a href='/guix/log/gnu?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>gnu</a>/<a href='/guix/log/gnu/packages?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>packages</a>/<a href='/guix/log/gnu/packages/rdf.scm?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46'>rdf.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/rdf.scm?id=bd19671f8a500f7bd5d17f8d08e4119a774acb46&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-01-18 19:35:56 +0100'>2022-01-18</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=2188af8bdff0ac74e216840ac46cf1580f23f66a'>gnu: python-sparqlwrapper: Build with older setuptools.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (python-sparqlwrapper)[native-inputs]: Add
PYTHON-SETUPTOOLS.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-01-18 19:35:55 +0100'>2022-01-18</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=ad5efcf4c076fd06c90c7f79a76f506aebf7c139'>gnu: python-rdflib-jsonld: Update to 0.6.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (python-rdflib-jsonld): Update to 0.6.2.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-01-18 19:35:55 +0100'>2022-01-18</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=2a4c271e614d069423519af4be5511a0c25156f1'>gnu: python-rdflib: Update to 6.1.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (python-rdflib): Update to 6.1.1.
[arguments]: Remove #:tests.  Add #:phases.
[native-inputs]: Change from PYTHON-NOSE to PYTHON-PYTEST.
(python-rdflib-5): New variable.
(python2-rdflib): Inherit from PYTHON-RDFLIB-5.
* gnu/packages/python-xyz.scm (python-prov): Change from PYTHON-RDFLIB to
PYTHON-RDFLIB-5.
* gnu/packages/bioinformatics.scm (cwltool): Likewise.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-01-05 03:54:05 +0100'>2022-01-05</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=8860e9db560c5d9e74277b608071fbb93579db4f'>gnu: lucene++: Use G-expressions.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (lucene++)[arguments]:
Rewrite as G-expressions.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2022-01-05 03:54:05 +0100'>2022-01-05</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=8e25b0f64a256d68da6066c5fde24eaf2df8b2b8'>gnu: lucene++: Update to 3.0.8.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (lucene++): Update to 3.0.8.
[source]: Add a nice snippet.
[arguments]: Don't install the entire gtest suite.
Add a custom 'check phase.
[inputs]: Add zlib.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=8394619baceb118df92e355377fd543bb1aa501a'>gnu: Simplify package inputs.</a><span class='msg-avail'>...<span class='msg-tooltip'>This commit was obtained by running:

  ./pre-inst-env guix style

without any additional argument.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-11-11 12:18:11 -0500'>2021-11-11</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=05e3638bb9275276fe7999f37ff4c5b000337319'>gnu: Move a few Python packages to (gnu packages python-build).</a><span class='msg-avail'>...<span class='msg-tooltip'>This is in prevision of updating python-pypa-build, which now requires
python-packaging and adding python-tomli, which requires python-six.

* gnu/packages/python-xyz.scm (python-six)
(python-six-bootstrap, python2-six-bootstrap)
(python-pyparsing, python2-pyparsing, python-pyparsing-2.4.7)
(python-packaging-bootstrap, python2-packaging-bootstrap): Move packages to...
* gnu/packages/python-build.scm: ... here.  Update python-parsing to latest.
* gnu/packages/python-xyz.scm (python-six, python-packaging): Adjust to
inherit from their bootstrap versions.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2021-07-21 13:36:09 +0200'>2021-07-21</span></td><td><a href='/guix/commit/gnu/packages/rdf.scm?id=281808170a2a5182f174d795232b80c1aaf30caf'>gnu: Add python-sparqlwrapper.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/rdf.scm (python-sparqlwrapper): New variable.
</span></span></td><td>Lars-Dominik Braun</td></tr>