I've found my build environment had other problems related to pkgconfig. I succeeded to build Qt 5.1.0 without errors. Unless others report the same issue, I think this bug may be marked as resolved.

Thank you.

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I'm trying to build Qt-5.0.2 from sources, it configures and builds successfully, but throws an error when I do "make install":

( test -e Makefile.WebKit2.Target || /usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtbase/bin/qmake /usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtwebkit/Source/WebKit2/Target.pri -o Makefile.WebKit2.Target ) && make -f Makefile.WebKit2.Target install
make[3]: Entering directory `/usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtwebkit/Source/WebKit2'
/usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtbase/bin/qmake -o Makefile.WebKit2.Target Target.pri
Project ERROR: Package x11 not found
make[3]: *** [Makefile.WebKit2.Target] Error 3
make[3]: Leaving directory `/usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtwebkit/Source/WebKit2'
make[2]: *** [sub-Target-pri-install_subtargets-ordered] Error 2
make[2]: Leaving directory `/usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtwebkit/Source/WebKit2'
make[1]: *** [sub-Source-WebKit2-WebKit2-pro-install_subtargets-ordered] Error 2
make[1]: Leaving directory `/usr/src/packages/qt-everywhere-opensource-src-5.0.2/qtwebkit'
make: *** [module-qtwebkit-install_subtargets] Error 2

If I go to the mentioned directory manually and trigger qmake manually it works fine.

I also tried a workaround mentioned on this page: http://qt-project.org/forums/viewreply/109427/ and it worked for me.