Add missing aarch64 configury bits

patches/darwin12

@@ -19,23 +19,7 @@ Index: libffi/configure
 ===================================================================
 --- libffi.orig/configure
 +++ libffi/configure
-@@ -6848,7 +6848,14 @@ s390*-*linux*|s390*-*tpf*|sparc*-*linux*
- 	    LD="${LD-ld} -m elf_i386_fbsd"
- 	    ;;
- 	  x86_64-*linux*)
--	    LD="${LD-ld} -m elf_i386"
-+	    case `/usr/bin/file conftest.o` in
-+	      *x86-64*)
-+	         LD="${LD-ld} -m elf32_x86_64"
-+	         ;;
-+	      *)
-+	         LD="${LD-ld} -m elf_i386"
-+	         ;;
-+	    esac
- 	    ;;
- 	  ppc64-*linux*|powerpc64-*linux*)
- 	    LD="${LD-ld} -m elf32ppclinux"
-@@ -14459,7 +14466,7 @@ case "$target" in
+@@ -14494,7 +14494,7 @@ case "$target" in
  $as_echo "#define FFI_EXEC_TRAMPOLINE_TABLE 1" >>confdefs.h
  
       ;;
@@ -48,7 +32,7 @@ Index: libffi/configure.ac
 ===================================================================
 --- libffi.orig/configure.ac
 +++ libffi/configure.ac
-@@ -361,7 +361,7 @@ case "$target" in
+@@ -366,7 +366,7 @@ case "$target" in
                   [Cannot use PROT_EXEC on this target, so, we revert to
                     alternative means])
       ;;