fix rpath in pc files (#921)

data/carla-native-plugin.pc

@@ -5,5 +5,5 @@ includedir=X-INCLUDEDIR-X/carla
 Name: carla-native-plugin
 Version: 1.9.14
 Description: Carla Native Plugin
-Libs: -Wl,rpath=${libdir} -L${libdir} -lcarla_native-plugin
+Libs: -Wl,-rpath=${libdir} -L${libdir} -lcarla_native-plugin
 Cflags: -DREAL_BUILD -I${includedir} -I${includedir}/includes

data/carla-standalone.pc

@@ -5,5 +5,5 @@ includedir=X-INCLUDEDIR-X/carla
 Name: carla-standalone
 Version: 1.9.14
 Description: Carla Host Standalone
-Libs: -Wl,rpath=${libdir} -L${libdir} -lcarla_standalone2
+Libs: -Wl,-rpath=${libdir} -L${libdir} -lcarla_standalone2
 Cflags: -DREAL_BUILD -I${includedir} -I${includedir}/includes

data/carla-utils.pc

@@ -5,5 +5,5 @@ includedir=X-INCLUDEDIR-X/carla
 Name: carla-utils
 Version: 1.9.14
 Description: Carla Host Utilities
-Libs: -Wl,rpath=${libdir} -L${libdir} -lcarla_utils
+Libs: -Wl,-rpath=${libdir} -L${libdir} -lcarla_utils
 Cflags: -DREAL_BUILD -I${includedir} -I${includedir}/includes -I${includedir}/utils