The moc executable loops through headers on CPLUS_INCLUDE_PATH and stumbles
on the GCC internal _GLIBCXX_VISIBILITY macro.  Tell it to ignore it as it is
not supposed to be looking there to begin with.

Upstream report: https://bugreports.qt.io/browse/QTBUG-83160

diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -188,6 +188,7 @@ int runMoc(int argc, char **argv)
     dummyVariadicFunctionMacro.arguments += Symbol(0, PP_IDENTIFIER, "__VA_ARGS__");
     pp.macros["__attribute__"] = dummyVariadicFunctionMacro;
     pp.macros["__declspec"] = dummyVariadicFunctionMacro;
+    pp.macros["_GLIBCXX_VISIBILITY"] = dummyVariadicFunctionMacro;
 
     QString filename;
     QString output;
value='1'/><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=67c3d230dc10fdd270acc5a0334a538de06e9c50'>refs</a><a class='active' href='/guix/log/gnu/packages/patches/elogind-fix-rpath.patch?showmsg=1'>log</a><a href='/guix/tree/gnu/packages/patches/elogind-fix-rpath.patch?id=67c3d230dc10fdd270acc5a0334a538de06e9c50'>tree</a><a href='/guix/commit/gnu/packages/patches/elogind-fix-rpath.patch?id=67c3d230dc10fdd270acc5a0334a538de06e9c50'>commit</a><a href='/guix/diff/gnu/packages/patches/elogind-fix-rpath.patch?id=67c3d230dc10fdd270acc5a0334a538de06e9c50'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/patches/elogind-fix-rpath.patch'>
<input type='hidden' name='id' value='67c3d230dc10fdd270acc5a0334a538de06e9c50'/><input type='hidden' name='showmsg' value='1'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=67c3d230dc10fdd270acc5a0334a538de06e9c50&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=67c3d230dc10fdd270acc5a0334a538de06e9c50&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=67c3d230dc10fdd270acc5a0334a538de06e9c50&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/patches?id=67c3d230dc10fdd270acc5a0334a538de06e9c50&amp;showmsg=1'>patches</a>/<a href='/guix/log/gnu/packages/patches/elogind-fix-rpath.patch?id=67c3d230dc10fdd270acc5a0334a538de06e9c50&amp;showmsg=1'>elogind-fix-rpath.patch</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/patches/elogind-fix-rpath.patch?id=67c3d230dc10fdd270acc5a0334a538de06e9c50'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2023-08-16 11:24:10 -0400'>2023-08-16</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/patches/elogind-fix-rpath.patch?id=132ddca5a4fb6d789f98866b5bf85be95306c969'>gnu: elogind: Update to 252.9.</a></td><td>Maxim Cournoyer</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/freedesktop.scm (elogind): Update to 252.9.
[source]: Replace elogind-revert-polkit-detection.patch with
elogind-fix-rpath.patch in patches.
[configure-flags]: Add the dbussystemservicedir, dbussessionservicedir,
dbussystemservicedir and dbus-interfaces-dir flags.
[phases] &lt;use-global-hook-directory&gt; Update list of patched files.
&lt;adjust-tests&gt; Update substitutions, and skip the copy_holes test.
[native-inputs]: Add python-jinja2.
[inputs]: Add util-linux:lib.
* gnu/services/desktop.scm (elogind-dbus-service)
&lt;elogind-dbus-service-wrapper&gt;: Add a symlink to elogind's
share/dbus-1/system.d to expose D-Bus policy configurations.
* gnu/tests/desktop.scm (run-elogind-test): Adjust expected result for the new
"linger" value.
* gnu/packages/patches/elogind-revert-polkit-detection.patch: Delete file.
* gnu/packages/patches/elogind-fix-rpath.patch: New file.
* gnu/local.mk (dist_patch_DATA): Update.

Series-to: 64938@debbugs.gnu.org
Series-prefix: elogind-updates
Series-version: 2
Series-changes: 2
- Fix elogind system test
- Install D-Bus policy files in elogind-dbus-service-wrapper
- Remove duplicate 'dbussystemservicedir' configure flag


</td></tr>