Bug 1357874 - Disable RegExp JIT for AArch64; r=snorp

I encountered crashes in jitted regexp code in my AArch64 Fennec build.
This patch disables that for now, but obviously we want to look into the
crashes and eventually turn this back on.

mobile/android/app/mobile.js

@@ -921,3 +921,7 @@ pref("webchannel.allowObject.urlWhitelist", "https://accounts.firefox.com https:
 pref("media.openUnsupportedTypeWithExternalApp", true);
 
 pref("dom.keyboardevent.dispatch_during_composition", true);
+
+#if CPU_ARCH == aarch64
+pref("javascript.options.native_regexp", false);
+#endif

mobile/android/app/moz.build

@@ -34,7 +34,7 @@ with Files('src/test/**'):
 for var in ('APP_NAME', 'APP_VERSION'):
     DEFINES[var] = CONFIG['MOZ_%s' % var]
 
-for var in ('MOZ_UPDATER', 'MOZ_APP_UA_NAME', 'ANDROID_PACKAGE_NAME'):
+for var in ('MOZ_UPDATER', 'MOZ_APP_UA_NAME', 'ANDROID_PACKAGE_NAME', 'CPU_ARCH'):
     DEFINES[var] = CONFIG[var]
 
 for var in ('MOZ_ANDROID_GCM', ):