contrib: Fontconfig workaround for weak symbols not found on Mac prio…

…r to Sierra.

When built with Xcode 8 and run on El Capitan or earlier, HandBrake could crash when attempting to burn soft subtitles.

contrib/fontconfig/module.defs

@@ -6,6 +6,11 @@ FONTCONFIG.FETCH.url     = https://download.handbrake.fr/handbrake/contrib/fontc
 FONTCONFIG.FETCH.url    += https://www.freedesktop.org/software/fontconfig/release/fontconfig-2.12.1.tar.bz2
 FONTCONFIG.FETCH.sha256  = b449a3e10c47e1d1c7a6ec6e2016cca73d3bd68fbbd4f0ae5cc6b573f7d6c7f3
 
+ifeq (1-darwin,$(FEATURE.xcode)-$(BUILD.system))
+    FONTCONFIG.CONFIGURE.env += ac_cv_func_mkostemp="no"
+    FONTCONFIG.BUILD.env += ac_cv_func_mkostemp="no"
+endif
+
 #
 # Under MinGW:
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