pixman: disable gtk

gtk is only needed to build test cases.
Disable it to simplify the build.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Makefile

diff --git a/Makefile b/Makefile
index ff2c16d..e68bb8f 100644
--- a/Makefile
+++ b/Makefile
@@ -122,7 +122,7 @@
 	$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C pixman V="$(V)" all,)
 
 pixman/Makefile: $(SRC_PATH)/pixman/configure
-	(cd pixman; $(SRC_PATH)/pixman/configure $(AUTOCONF_HOST) --disable-shared --enable-static)
+	(cd pixman; $(SRC_PATH)/pixman/configure $(AUTOCONF_HOST) --disable-gtk --disable-shared --enable-static)
 
 $(SRC_PATH)/pixman/configure:
 	(cd $(SRC_PATH)/pixman; autoreconf -v --install)