Drop libratbag as separate library

Now that ratbagd is part of libratbag, the DBus interface is the preferred way
to interact with a device. Shipping libratbag as a .so file means we have to
worry about two ABIs when it's unlikely that anyone ever uses the libratbag.so
directly.

Make it a static library internally instead.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/libratbag.pc.in

@@ -1,12 +0,0 @@
-prefix=@prefix@
-datadir=${prefix}/@datadir@
-pkgdatadir=${datadir}/libratbag
-libdir=${prefix}/@libdir@
-includedir=${prefix}/@includedir@
-
-Name: Libratbag
-Description: Mouse configuration library
-Version: @LIBRATBAG_VERSION@
-Cflags: -I${includedir}
-Libs: -L${libdir} -lratbag
-Libs.private: -lm -lrt