configure: respect $libdir for the OMX installation dir

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
diff --git a/configure.ac b/configure.ac
index bc589b7..c37018f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1794,16 +1794,13 @@
     [VDPAU_LIB_INSTALL_DIR='${libdir}/vdpau'])
 AC_SUBST([VDPAU_LIB_INSTALL_DIR])
 
-OMX_LIB_INSTALL_DIR_DEFAULT=''
-if test "x$enable_omx" = xyes; then
-    OMX_LIB_INSTALL_DIR_DEFAULT=`$PKG_CONFIG --variable=pluginsdir libomxil-bellagio`
-fi
+dnl Directory for OMX libs
 
 AC_ARG_WITH([omx-libdir],
     [AS_HELP_STRING([--with-omx-libdir=DIR],
         [directory for the OMX libraries])],
     [OMX_LIB_INSTALL_DIR="$withval"],
-    [OMX_LIB_INSTALL_DIR="$OMX_LIB_INSTALL_DIR_DEFAULT"])
+    [OMX_LIB_INSTALL_DIR=`$PKG_CONFIG --define-variable=libdir=\$libdir --variable=pluginsdir libomxil-bellagio`])
 AC_SUBST([OMX_LIB_INSTALL_DIR])
 
 dnl Directory for VA libs