Qt contribs are built linking towards the building contrib folder instead of the prefix

Regression from !2479 (merged)

╰─$ cat build-win64/contrib/x86_64-w64-mingw32/lib/pkgconfig/qwindows.pc                                                          130 ↵
prefix=/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32
exec_prefix=${prefix}
libdir=/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms
includedir=${prefix}/include


Name: Qwindows
Description: Qwindows Plugin
Version: 5.15.1
Cflags:

Libs:  -L${libdir} -lqwindows  -ldwmapi -lwinspool -lshlwapi -lwtsapi32 /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5EventDispatcherSupport.a -L/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5FontDatabaseSupport.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libqtfreetype.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5ThemeSupport.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5AccessibilitySupport.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5WindowsUIAutomationSupport.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5Gui.a -ld3d11 -ldxgi /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libqtlibpng.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libqtharfbuzz.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libQt5Core.a -lmpr -luserenv -lversion /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libqtpcre2.a -lnetapi32 -lkernel32 -lshell32 /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/liblibEGL.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/liblibGLESv2.a -lcomdlg32 -loleaut32 -limm32 -lwinmm -lws2_32 -lole32 -ladvapi32 /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libtranslator.a /home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib/libpreprocessor.a -ld3d9 -ldxguid -lgdi32 -luser32 -luuid -lgdi32 -ladvapi32 -lole32 -lshell32 -luser32 -lwinmm
Requires:  

The Makefile doesn't fix the path as opposed to Qt:

# qt/src/corelib/Makefile.Debug
install_target: first FORCE
        @test -d $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-ming
w32/lib || mkdir -p $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-m
ingw32/lib
        $(SED)  -e 's,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib,$$$$[QT_INSTALL_LIBS],g' -e 's,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib,$$$$[QT_INSTALL_LIBS],g' ../../lib/Qt5Core.prl > $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib/Qt5Core.prl
        @test -d $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib/pkgconfig || mkdir -p $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib/pkgconfig
        $(SED)  -e s,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib,g ../../lib/pkgconfig/Qt5Core.pc > $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib/pkgconfig/Qt5Core.pc
        -$(INSTALL_FILE) $(DESTDIR_TARGET) $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib/$(TARGET)

# qt/src/plugins/platforms/windows/Makefile.Debug
install_target: first FORCE
        @test -d $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms || mkdir -p $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib
/x86_64-w64-mingw32/plugins/platforms
        $(SED)  -e 's,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/contrib-win64/qt/lib,$$$$[QT_INSTALL_LIBS],g' -e 's,/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/lib,$$$$[QT_INSTALL_LIBS],g' ../../../../plugins/platforms/qwindows.prl > $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms/qwindows.prl
        @test -d $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms || mkdir -p $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms
        $(INSTALL_FILE) ../../../../plugins/platforms/qwindows.pc $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms/qwindows.pc
        -$(INSTALL_FILE) $(DESTDIR_TARGET) $(INSTALL_ROOT:@msyshack@%=%)/home/janniaux/Projects/videolabs/vlc/build-win64/contrib/x86_64-w64-mingw32/plugins/platforms/$(TARGET)