configure: unbreak cross-pkg-config support with contrib

cross-pkg-config tools have a correct default search path. The contrib
path should complement it, not replace it. If the caller intends to
(ab)use the native pkg-config for cross-compilation, the caller is
responsible for selecting an adequate default path, not VLC configure,
just as with every other build tools.

configure.ac

@@ -375,11 +375,7 @@ AS_IF([test -n "${CONTRIB_DIR}"], [
   CFLAGS="${CFLAGS} -I${CONTRIB_DIR}/include"
   CXXFLAGS="${CXXFLAGS} -I${CONTRIB_DIR}/include"
   OBJCFLAGS="${OBJCFLAGS} -I${CONTRIB_DIR}/include"
-  AS_IF([test "$build" = "$host" -o "$PKG_CONFIG_LIBDIR"], [
-    export PKG_CONFIG_PATH="${CONTRIB_DIR}/lib/pkgconfig:$PKG_CONFIG_PATH"
-  ], [
-    export PKG_CONFIG_LIBDIR="${CONTRIB_DIR}/lib/pkgconfig"
-  ])
+  export PKG_CONFIG_PATH="${CONTRIB_DIR}/lib/pkgconfig:$PKG_CONFIG_PATH"
   LDFLAGS="${LDFLAGS} -L${CONTRIB_DIR}/lib"
 
   AS_IF([test "${SYS}" = "darwin"], [