meson: fix up wrong escaping of variables in .pc file and missing variables in -uninstalled.pc file
requested to merge tpm/gst-plugins-base:meson-gst-gl-pkg-config-winsys-api-platform-variable-escaping into master
Obviously a bit of a hack, but maybe ok as a workaround for now?
Workaround for pkg.generate() escaping spaces in pc variables that shouldn't be escaped. Perhaps going back to configure_file() would be a better option though.
Fixes #884 (closed)