build: add variables to pkgconfig and dep files

 - pluginsdir: to set BABL_PATH
 - girdir: location of introspection gir file
 - typelibdir: location of introspection typelib file
2 jobs for subproject in 3 minutes and 10 seconds
Status Job ID Name Coverage
  Build
passed #1215110
latest-lcms

00:03:08

passed #1215111
latest-nolcms

00:03:10