Respect non-standard install paths for web interface files

libtransmission/Makefile.am

@@ -1,4 +1,8 @@
-AM_CPPFLAGS = -I. -I$(top_srcdir) -I$(top_srcdir)/third-party/ -D__TRANSMISSION__ $(LIBEVENT_CPPFLAGS)
+AM_CPPFLAGS = \
+	-I. -I$(top_srcdir) -I$(top_srcdir)/third-party/ \
+	-D__TRANSMISSION__ $(LIBEVENT_CPPFLAGS) \
+	-DPACKAGE_DATA_DIR=\""$(datadir)"\"
+
 AM_CFLAGS = $(LIBCURL_CFLAGS) $(OPENSSL_CFLAGS) $(PTHREAD_CFLAGS)
 
 noinst_LIBRARIES = libtransmission.a

libtransmission/platform.c

@@ -563,7 +563,7 @@ tr_getClutchDir( const tr_session * session UNUSED )
             /* XDG_DATA_DIRS are the backup directories */
             s = getenv( "XDG_DATA_DIRS" );
             if( !s || !*s )
-                s = "/usr/local/share/:/usr/share/";
+                s =  PACKAGE_DATA_DIR ":/usr/local/share/:/usr/share/";
             while( s && *s ) {
                 char * end = strchr( s, ':' );
                 if( end ) {