third_party: Add support for building libffi for ARM.

third_party/libffi/include/arm-unknown-linux-gnu/include/ffitarget.h

Index: third_party/libffi/include/arm-unknown-linux-gnu/include/ffitarget.h
diff --git a/third_party/libffi/include/arm-unknown-linux-gnu/include/ffitarget.h b/third_party/libffi/include/arm-unknown-linux-gnu/include/ffitarget.h
new file mode 100644
index 0000000000000000000000000000000000000000..26d494d616a22641c558abe87ffa3753bab5f11b
--- /dev/null
+++ b/third_party/libffi/include/arm-unknown-linux-gnu/include/ffitarget.h
@@ -0,0 +1,71 @@
+/* -----------------------------------------------------------------*-C-*-
+   ffitarget.h - Copyright (c) 2012  Anthony Green
+                 Copyright (c) 2010  CodeSourcery
+                 Copyright (c) 1996-2003  Red Hat, Inc.
+
+   Target configuration macros for ARM.
+
+   Permission is hereby granted, free of charge, to any person obtaining
+   a copy of this software and associated documentation files (the
+   ``Software''), to deal in the Software without restriction, including
+   without limitation the rights to use, copy, modify, merge, publish,
+   distribute, sublicense, and/or sell copies of the Software, and to
+   permit persons to whom the Software is furnished to do so, subject to
+   the following conditions:
+
+   The above copyright notice and this permission notice shall be included
+   in all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
+   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+   NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+   DEALINGS IN THE SOFTWARE.
+
+   ----------------------------------------------------------------------- */
+
+#ifndef LIBFFI_TARGET_H
+#define LIBFFI_TARGET_H
+
+#ifndef LIBFFI_H
+#error "Please do not include ffitarget.h directly into your source.  Use ffi.h instead."
+#endif
+
+#ifndef LIBFFI_ASM
+typedef unsigned long          ffi_arg;
+typedef signed long            ffi_sarg;
+
+typedef enum ffi_abi {
+  FFI_FIRST_ABI = 0,
+  FFI_SYSV,
+  FFI_VFP,
+  FFI_LAST_ABI,
+#ifdef __ARM_PCS_VFP
+  FFI_DEFAULT_ABI = FFI_VFP,
+#else
+  FFI_DEFAULT_ABI = FFI_SYSV,
+#endif
+} ffi_abi;
+#endif
+
+#define FFI_EXTRA_CIF_FIELDS			\
+  int vfp_used;					\
+  short vfp_reg_free, vfp_nargs;		\
+  signed char vfp_args[16]			\
+
+/* Internally used. */
+#define FFI_TYPE_STRUCT_VFP_FLOAT  (FFI_TYPE_LAST + 1)
+#define FFI_TYPE_STRUCT_VFP_DOUBLE (FFI_TYPE_LAST + 2)
+
+#define FFI_TARGET_SPECIFIC_VARIADIC
+
+/* ---- Definitions for closures ----------------------------------------- */
+
+#define FFI_CLOSURES 1
+#define FFI_TRAMPOLINE_SIZE 20
+#define FFI_NATIVE_RAW_API 0
+
+#endif