gnu: libffi: fix handling of uint32_t arguments on MIPS N32.

* gnu/packages/patches/libffi-mips-n32-fix.patch: New file.
* gnu/packages/libffi.scm (libffi): Add patch.
* gnu-system.am (dist_patch_DATA): Add patch.

gnu-system.am

@@ -237,6 +237,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/guile-relocatable.patch			\
   gnu/packages/patches/hop-bigloo-4.0b.patch			\
   gnu/packages/patches/libevent-dns-tests.patch			\
+  gnu/packages/patches/libffi-mips-n32-fix.patch		\
   gnu/packages/patches/libtool-skip-tests.patch			\
   gnu/packages/patches/libtool-skip-tests-for-mips.patch	\
   gnu/packages/patches/m4-gets-undeclared.patch			\

gnu/packages/libffi.scm

@@ -17,6 +17,7 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (gnu packages libffi)
+  #:use-module (gnu packages)
   #:use-module (guix licenses)
   #:use-module (guix packages)
   #:use-module (guix download)
@@ -46,7 +47,8 @@
                              name "-" version ".tar.gz"))
              (sha256
               (base32
-               "077ibkf84bvcd6rw1m6jb107br63i2pp301rkmsbgg6300adxp8x"))))
+               "077ibkf84bvcd6rw1m6jb107br63i2pp301rkmsbgg6300adxp8x"))
+             (patches (list (search-patch "libffi-mips-n32-fix.patch")))))
     (build-system gnu-build-system)
     (arguments `(#:modules ((guix build utils) (guix build gnu-build-system)
                             (ice-9 ftw) (srfi srfi-26))

gnu/packages/patches/libffi-mips-n32-fix.patch

@@ -0,0 +1,21 @@
+Fix handling of uint32_t arguments on the MIPS N32 ABI.
+
+Patch by Mark H Weaver <mhw@netris.org>.
+
+--- libffi/src/mips/ffi.c.orig	2013-03-16 07:19:39.000000000 -0400
++++ libffi/src/mips/ffi.c	2013-10-22 01:11:03.111985247 -0400
+@@ -170,7 +170,14 @@
+ 		break;
+ 		  
+ 	      case FFI_TYPE_UINT32:
++#ifdef FFI_MIPS_N32
++		/* The N32 ABI requires that 32-bit integers
++		   be sign-extended to 64-bits, regardless of
++		   whether they are signed or unsigned. */
++		*(ffi_arg *)argp = *(SINT32 *)(* p_argv);
++#else
+ 		*(ffi_arg *)argp = *(UINT32 *)(* p_argv);
++#endif
+ 		break;
+ 
+ 	      /* This can only happen with 64bit slots.  */