Fix pkg-config files

openwebrtc-0.1.pc listed ${includedir}/libopenwebrtc-0.1 as include directory
but that does not exist and is wrong. We currently use ${includedir} directly.

openwebrtc-bridge-0.1.pc was not properly autogenerated and no substitution of
variables happened, making it effectively unusable.

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Independent of that, we currently don't properly version the library filename (libopenwebrtc vs libopenwebrtc-0.1) and also not the include directory (include/owr vs include/owr-0.1/owr). I'll open a ticket for that.