MoonchildProductions#1251 - Part 11: libpng uses C89 now to avoid buffer overflows.

https://bugzilla.mozilla.org/show_bug.cgi?id=1371266
https://github.com/glennrp/libpng/commit/12e63e91af1378225993b36e25ce3252b54e751a

This sounds absurd, and the fact that we had to change a C++ comment to a C-style comment on account of this may seem hilarious and inconsequential, but this isapparently not a joke and leaving it as it is now may be a bad idea.

media/libpng/moz.build

@@ -51,3 +51,6 @@ FINAL_LIBRARY = 'gkmedias'
 
 # We allow warnings for third-party code that can be updated from upstream.
 ALLOW_COMPILER_WARNINGS = True
+
+if CONFIG['GNU_CC']
+    CFLAGS += ['std=c89']

mozilla-config.h.in

@@ -13,7 +13,7 @@
 #endif
 #endif
 
-// Expands to all the defines from configure.
+/* Expands to all the defines from configure. */
 #undef ALLDEFINES
 
 /*