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}

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<div class='path'>path: <a href='/guix/log/?id=304cf4e7eed8082700ef7f63a3cd4c2bc93f2091'>root</a>/<a href='/guix/log/tests?id=304cf4e7eed8082700ef7f63a3cd4c2bc93f2091'>tests</a>/<a href='/guix/log/tests/build-utils.scm?id=304cf4e7eed8082700ef7f63a3cd4c2bc93f2091'>build-utils.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/tests/build-utils.scm?id=304cf4e7eed8082700ef7f63a3cd4c2bc93f2091&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2016-04-03 14:19:09 +0200'>2016-04-03</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=a9edb211e733b8b34e67ec3b4450567e9376986f'>build: Add a Guile custom test driver using SRFI-64.</a><span class='msg-avail'>...<span class='msg-tooltip'>Before that '.log' files for scheme tests were fragmented and not
included in test-suite.log.  This unifies the semantics of SRFI-64 API
with Automake test suite.

* build-aux/test-driver.scm: New file.
* Makefile.am (SCM_LOG_DRIVER, AM_SCM_LOG_DRIVER_FLAGS): New variables.
(SCM_LOG_COMPILER, AM_SCM_LOG_FLAGS): Delete variables.
(AM_TESTS_ENVIRONMENT): Set GUILE_AUTO_COMPILE to 0.
* test-env.in: Silence guix-daemon.
* doc/guix.texi (Running the Test Suite): Describe how to display the
detailed results.  Bug reports require only 'test-suite.log' file.
* tests/base32.scm, tests/build-utils.scm, tests/builders.scm,
tests/challenge.scm, tests/cpan.scm, tests/cpio.scm, tests/cran.scm,
tests/cve.scm, tests/derivations.scm, tests/elpa.scm,
tests/file-systems.scm, tests/gem.scm, tests/gexp.scm,
tests/gnu-maintenance.scm, tests/grafts.scm, tests/graph.scm,
tests/gremlin.scm, tests/hackage.scm, tests/hash.scm,
tests/import-utils.scm, tests/lint.scm, tests/monads.scm, tests/nar.scm,
tests/packages.scm, tests/pk-crypto.scm, tests/pki.scm,
tests/profiles.scm, tests/publish.scm, tests/pypi.scm,
tests/records.scm, tests/scripts-build.scm, tests/scripts.scm,
tests/services.scm, tests/sets.scm, tests/size.scm, tests/snix.scm,
tests/store.scm, tests/substitute.scm, tests/syscalls.scm,
tests/system.scm, tests/ui.scm, tests/union.scm, tests/upstream.scm,
tests/utils.scm: Don't exit at the end of test groups.
* tests/containers.scm: Likewise.  Use 'test-skip' instead of exiting
with error code 77.
</span></span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2015-09-24 21:21:02 +0200'>2015-09-24</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=12cd4dd3a9052491e3912ffeecbe8854ea9b971a'>tests: Unset 'LOCPATH' before running bootstrap program.</a><span class='msg-avail'>...<span class='msg-tooltip'>Reported by Mark H Weaver &lt;mhw@netris.org&gt;.

* tests/build-utils.scm ("wrap-program, one input, multiple calls"): Add
  'unsetenv' call.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2014-09-13 21:53:21 -0500'>2014-09-13</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=de61113857d3ebda1f4557c5a8f6bffe63100060'>utils: Allow wrap-program to be called multiple times.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/utils.scm (wrap-program): Multiple invocations of
  wrap-program for the same file create successive wrappers.  Adjust
  docstring.
* tests/build-utils.scm: Test new wrap-program behavior.
  (%store): New variable.
</span></span></td><td>Eric Bavier</td></tr>