Bug 1305677 - Remove requirement of libffi on aarch64 as default. r=chmanchester

To support android/aarch64, I want to remove the requirement of system's libffi.

MozReview-Commit-ID: Lc3POx09Cks

--HG--
extra : rebase_source : 384852e7b9e61d0d7a950159535e3ddc8457e889

build/moz.configure/ffi.configure

@@ -7,7 +7,7 @@
 @depends(target)
 def force_system_ffi(target):
     # Pre-emptively move to system ffi for non-tier one platforms.
-    if target.cpu not in ('x86', 'x86_64', 'arm'):
+    if target.cpu not in ('x86', 'x86_64', 'arm', 'aarch64'):
         return True
 
 imply_option('--with-system-ffi', force_system_ffi, "target")
@@ -28,7 +28,7 @@ add_old_configure_assignment('MOZ_SYSTEM_FFI', system_ffi)
 # Target selection, based on ffi/configure.ac.
 @depends_when(target, when=building_ffi)
 def ffi_target(target):
-    if target.cpu not in ('x86', 'x86_64', 'arm'):
+    if target.cpu not in ('x86', 'x86_64', 'arm', 'aarch64'):
         die('Building libffi from the tree is not supported on this platform. '
             'Use --with-system-ffi instead.')
 
@@ -44,6 +44,9 @@ def ffi_target(target):
     elif target.cpu == 'arm':
         target_dir = 'arm'
         target_name = 'ARM'
+    elif target.cpu == 'aarch64':
+        target_dir = 'aarch64'
+        target_name = 'AARCH64'
     else:
         target_dir = 'x86'
         target_name = target.cpu.upper()

config/external/ffi/moz.build

@@ -78,6 +78,8 @@ else:
         ffi_srcs = ('sysv.S', 'ffi.c')
         if CONFIG['CLANG_CXX']:
             ASFLAGS += ['-no-integrated-as']
+    elif CONFIG['FFI_TARGET'] == 'AARCH64':
+        ffi_srcs = ('sysv.S', 'ffi.c')
     elif CONFIG['FFI_TARGET'] == 'X86':
         ffi_srcs = ('ffi.c', 'sysv.S', 'win32.S')
     elif CONFIG['FFI_TARGET'] == 'X86_64':