Bug 1469790 - Build for NEON by default when targetting Android arm. r=nalexander

The media/libpng/moz.build file overrides the C standard used via
-std=c89, per bug 1371266, which conflicts with the use of the
arm_neon.h header: compilation fails on the inline keyword, which didn't
exist in C89. We thus "bump" to the GNU89 standard, which is C89+GNU
extensions, including inline.

--HG--
extra : rebase_source : fe93a13e3bef8888e1874d2e94a6d8ef396aaf83

build/autoconf/arch.m4

@@ -31,7 +31,7 @@ if test -z "$MOZ_ARCH"; then
     arm-Android)
         MOZ_THUMB=yes
         MOZ_ARCH=armv7-a
-        MOZ_FPU=vfpv3-d16
+        MOZ_FPU=neon
         MOZ_FLOAT_ABI=softfp
         MOZ_ALIGN=no
         ;;

media/libpng/moz.build

@@ -66,4 +66,4 @@ FINAL_LIBRARY = 'gkmedias'
 AllowCompilerWarnings()
 
 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-    CFLAGS += ['-std=c89']
+    CFLAGS += ['-std=gnu89']