libffi: make this work correctly on musl; patch via Alpine.

See http://bugs.alpinelinux.org/issues/4275

srcpkgs/libffi/patches/libffi-fix-define-for-musl.patch

@@ -0,0 +1,13 @@
+http://bugs.alpinelinux.org/issues/4275
+
+--- src/closures.c.orig
++++ src/closures.c
+@@ -34,7 +34,7 @@
+ #include <ffi_common.h>
+
+ #if !FFI_MMAP_EXEC_WRIT && !FFI_EXEC_TRAMPOLINE_TABLE
+-# if __gnu_linux__ && !defined(__ANDROID__)
++# if __linux__ && !defined(__ANDROID__)
+ /* This macro indicates it may be forbidden to map anonymous memory
+    with both write and execute permission.  Code compiled when this
+    option is defined will attempt to map such pages once, but if it

srcpkgs/libffi/template

@@ -1,7 +1,7 @@
 # Template file for 'libffi'
 pkgname=libffi
 version=3.2.1
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--includedir=/usr/include --with-pic"
 short_desc="Library supporting Foreign Function Interfaces"