Add fix for on-device iOS trampoline failure.

Author: freakboy3742

patch/libffi.patch

@@ -279,3 +279,42 @@ index 9921b0d..5b60ccc 100755
 
      mkdir_p('darwin_common/include')
      for header_name, tag_tuples in platform_headers.items():
+diff --git a/src/closures.c b/src/closures.c
+index f7bead6..db7ec94 100644
+--- a/src/closures.c
++++ b/src/closures.c
+@@ -134,7 +134,7 @@ ffi_tramp_is_present (__attribute__((unused)) void *ptr)
+ #  define HAVE_MNTENT 1
+ # endif
+ # if defined(_WIN32) || defined(__OS2__)
+-/* Windows systems may have Data Execution Protection (DEP) enabled, 
++/* Windows systems may have Data Execution Protection (DEP) enabled,
+    which requires the use of VirtualMalloc/VirtualFree to alloc/free
+    executable memory. */
+ #  define FFI_MMAP_EXEC_WRIT 1
+@@ -230,12 +230,24 @@ ffi_trampoline_table_alloc (void)
+   kt = vm_remap (mach_task_self (), &trampoline_page, PAGE_MAX_SIZE, 0x0,
+ 		 VM_FLAGS_OVERWRITE, mach_task_self (), trampoline_page_template,
+ 		 FALSE, &cur_prot, &max_prot, VM_INHERIT_SHARE);
+-  if (kt != KERN_SUCCESS || !(cur_prot & VM_PROT_EXECUTE))
++  if (kt != KERN_SUCCESS)
+     {
+       vm_deallocate (mach_task_self (), config_page, PAGE_MAX_SIZE * 2);
+       return NULL;
+     }
+ 
++  if (!(cur_prot & VM_PROT_EXECUTE))
++    {
++      /* If VM_PROT_EXECUTE isn't set on the remapped trampoline page, set it */
++      kt = vm_protect (mach_task_self (), trampoline_page, PAGE_MAX_SIZE,
++         FALSE, cur_prot | VM_PROT_EXECUTE);
++      if (kt != KERN_SUCCESS)
++        {
++          vm_deallocate (mach_task_self (), config_page, PAGE_MAX_SIZE * 2);
++          return NULL;
++        }
++    }
++
+   /* We have valid trampoline and config pages */
+   table = calloc (1, sizeof (ffi_trampoline_table));
+   table->free_count = FFI_TRAMPOLINE_COUNT;