AArch64: Port to Android
AArch64: Port to Android

Bionic doesn't support getcontext(), work around that.

Change-Id: Iab6e5a5ec99716c54a69dbc2b227fbbf9408fb47
Signed-off-by: Kévin PETIT <9b79a2d3df4408bbf6fcf0c9904434a8637f93cf@arm.com>

androidarmv6/android_external_libunwind,geekboxzone/mmallow_external_libunwind,androidarmv6/android_external_libunwind,androidarmv6/android_external_libunwind,zeldin/platform_external_libunwind,DroidSim/platform_external_libunwind,atanasyan/libunwind-android,geekboxzone/mmallow_external_libunwind,maltek/platform_external_libunwind,frida/libunwind,frida/libunwind,android-ia/platform_external_libunwind,CyanogenMod/android_external_libunwind,geekboxzone/lollipop_external_libunwind,CyanogenMod/android_external_libunwind,maltek/platform_external_libunwind,maltek/platform_external_libunwind,CyanogenMod/android_external_libunwind,SyndicateRogue/libunwind,frida/libunwind,SyndicateRogue/libunwind,android-ia/platform_external_libunwind,zeldin/platform_external_libunwind,geekboxzone/lollipop_external_libunwind,geekboxzone/mmallow_external_libunwind,olibc/libunwind,android-ia/platform_external_libunwind,atanasyan/libunwind-android,atanasyan/libunwind-android,olibc/libunwind,geekboxzone/lollipop_external_libunwind,SyndicateRogue/libunwind,zeldin/platform_external_libunwind,DroidSim/platform_external_libunwind,DroidSim/platform_external_libunwind,olibc/libunwind