Update PKG_CONFIG_PATH paths to include more platforms
Update PKG_CONFIG_PATH paths to include more platforms

Add platform-specific directories to pkg_config search paths,
and fix a build time issue on some platforms.

Reported by Milos Koprla (milos.koprla@sowhat.sk).

Signed-off-by: Krzysztof Wilczyński <5f1c0be89013f8fde969a8dcb2fa1d522e94ee00@linux.com>

kwilczynski/ruby-magic,kwilczynski/ruby-magic