Otherwise we end up with missing -I/usr/include/raptor2 for raptor.h

--- configure.ac
+++ configure.ac
@@ -742,6 +742,7 @@
 		AC_MSG_CHECKING(whether liblrdf version >= 0.4.0)
 		if `pkg-config --exists 'lrdf >= 0.4.0'`; then
 			AC_MSG_RESULT(yes)
+			lrdf_CFLAGS=`pkg-config --cflags lrdf`
 		        lrdf_LIBS=`pkg-config --libs lrdf`
 			AC_DEFINE([HAVE_LADSPA], [1], [Defined if compile with LADSPA plugin support])
 		else
@@ -957,7 +958,7 @@
 
 CFLAGS="$CFLAGS $BUILD_CFLAGS -Wall $PLATFORM_CFLAGS $AQUALUNG_SKINDIR $AQUALUNG_LOCALEDIR $AQUALUNG_DATADIR -D_GNU_SOURCE"
 CXXFLAGS="$CFLAGS"
-CPPFLAGS="$gtk_CFLAGS $glib_CFLAGS $xml_CFLAGS $alsa_CFLAGS $jack_CFLAGS $cdda_CFLAGS $pulse_CFLAGS"
+CPPFLAGS="$gtk_CFLAGS $glib_CFLAGS $xml_CFLAGS $alsa_CFLAGS $jack_CFLAGS $cdda_CFLAGS $pulse_CFLAGS $lrdf_CFLAGS"
 LIBS="decoder/libdecoder.a encoder/libencoder.a $gtk_LIBS $glib_LIBS $xml_LIBS $jack_LIBS $lrdf_LIBS $src_LIBS $alsa_LIBS $sndio_LIBS $oss_LIBS $sndfile_LIBS $flac_LIBS $ogg_LIBS $wavpack_LIBS $speex_LIBS $mad_LIBS $mod_LIBS $mpc_LIBS $mac_LIBS $lavc_LIBS $vorbisenc_LIBS $lame_LIBS $cdda_LIBS $cddb_LIBS $ifp_LIBS $PLATFORM_LIBS $z_LIBS $bz2_LIBS $lua_LIBS $pulse_LIBS"