libffi: Patch for building with clang on arm

packages/libffi/src-arm-sysv.S.patch

@@ -0,0 +1,17 @@
+Patch to allow building libffi using clang:
+  https://github.com/libffi/libffi/issues/191
+
+Can be dropped after the next libffi release.
+
+diff -u -r ../libffi-3.2.1/src/arm/sysv.S ./src/arm/sysv.S
+--- ../libffi-3.2.1/src/arm/sysv.S	2014-11-08 07:47:24.000000000 -0500
++++ ./src/arm/sysv.S	2016-05-16 20:37:25.684302345 -0400
+@@ -396,7 +396,7 @@
+ 	beq	LSYM(Lepilogue_vfp)
+ 
+ 	cmp	r3, #FFI_TYPE_SINT64
+-	stmeqia	r2, {r0, r1}
++	stmiaeq	r2, {r0, r1}
+ 	beq	LSYM(Lepilogue_vfp)
+ 
+ 	cmp	r3, #FFI_TYPE_FLOAT