libevas: async image preload support needs threads support in toolchain

Fixes http://autobuild.buildroot.net/results/92b/92b3990e3a51c9e400cff31a1f0d23aeb5085a54/

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/efl/libevas/libevas.mk

@@ -203,6 +203,11 @@ else
 LIBEVAS_CONF_OPT += --disable-font-loader-eet
 endif
 
+# async image preload support needs threads support in toolchain
+ifneq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
+LIBEVAS_CONF_OPT += --disable-async-preload
+endif
+
 # libevas installs the source code of examples on the target, which
 # are generally not useful.
 define LIBEVAS_REMOVE_EXAMPLES