moc does not take pkgconfig cflags into account

When using pkg-config via

CONFIG += link_pkgconfig
PKGCONFIG += pkgconfig-file.pc

moc does not get the relevant include directories from the pkgconfig file.

link_pkgconfig only fills up the CFLAGS, CXXFLAGS and LIBS variables, but moc uses DEFINES and INCLUDEPATH.

Currently something like
INCLUDEPATH += $$system(pkg-config -cflags pkgconfig-file | tr \' \' \'\\n\' | grep ^-I | cut -d I -f 2)
is required to fix INCLUDEPATH by hand. It would be great if that could be done by link_pkgconfig automatically (same with DEFINES).