libs: glib2: fix provided pkg-config and always use host tools

[Ansuel]

For the InstallDev target, the pkg-config should point to the glib2 host tools for glib_compile_resources, gdbus_codegen, glib_genmarshal and glib_mkenums instead of pointing to the targets ones as they are unusable by the host machine (due to crosscompiling)

Fix the pkg-config to reference the host tools by replaying the entry and use the prefix_hostpkg variable provided by our pkg-config.

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This fix the recent error with grilo-plugins trying to use target glib_compile_resources instead of the host one.