qtmultimedia: inherit pkgconfig
qtmultimedia: inherit pkgconfig

* some features enabled with PACKAGECONFIG need pkgconfig to
  be detected correctly

* fixes:
  | Checking for libresourceqt5... ERROR: Error calling /OE/build/luneos-honister/webos-ports/tmp-glibc/work/core2-64-webos-linux/qtmultimedia/5.15.2+gitAUTOINC+fd30913d46-r0/recipe-sysroot-native/usr/bin/qmake -makefile -o Makefile    QT_BUILD_PARTS-=examples QT_BUILD_PARTS-=tests   /OE/build/luneos-honister/webos-ports/tmp-glibc/work/core2-64-webos-linux/qtmultimedia/5.15.2+gitAUTOINC+fd30913d46-r0/git/qtmultimedia.pro  --   -alsa -gstreamer 1.0 -no-feature-openal -pulseaudio
  | no
  | Done running configuration tests.
  ...
  | ERROR: Feature 'gstreamer_1_0' was enabled, but the pre-condition 'libs.gstreamer_1_0' failed.
  |
  | ERROR: Feature 'pulseaudio' was enabled, but the pre-condition 'libs.pulseaudio' failed.

meta-qt5/meta-qt5,meta-qt5/meta-qt5