freetype: fix host build

Fixes http://autobuild.buildroot.net/results/b49/b49c1c502215c7972d61c900e876909c9e79c312/

PNG support has to be explictly disabled now.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/freetype/freetype.mk

@@ -19,6 +19,7 @@ FREETYPE_DEPENDENCIES = host-pkgconf \
 FREETYPE_CONFIG_SCRIPTS = freetype-config
 
 HOST_FREETYPE_DEPENDENCIES = host-pkgconf
+HOST_FREETYPE_CONF_OPT = --without-png
 
 ifeq ($(BR2_PACKAGE_LIBPNG),y)
 FREETYPE_DEPENDENCIES += libpng