Pulled in libffi from gcc trunk.

Fixed build and install for standalone use.

libffi/testsuite/libffi.call/cls_double.c

@@ -0,0 +1,51 @@
+/* Area:	closure_call
+   Purpose:	Check return value double.
+   Limitations:	none.
+   PR:		none.
+   Originator:	<andreast@gcc.gnu.org> 20030828	 */
+
+/* { dg-do run { xfail mips64*-*-* arm*-*-* strongarm*-*-* xscale*-*-* } } */
+#include "ffitest.h"
+
+static void cls_ret_double_fn(ffi_cif* cif __UNUSED__, void* resp, void** args,
+			      void* userdata __UNUSED__)
+ {
+   *(double *)resp = *(double *)args[0];
+
+   printf("%f: %f\n",*(double *)args[0],
+	  *(double *)resp);
+ }
+typedef double (*cls_ret_double)(double);
+
+int main (void)
+{
+  ffi_cif cif;
+#ifndef USING_MMAP
+  static ffi_closure cl;
+#endif
+  ffi_closure *pcl;
+  ffi_type * cl_arg_types[2];
+  double res;
+
+#ifdef USING_MMAP
+  pcl = allocate_mmap (sizeof(ffi_closure));
+#else
+  pcl = &cl;
+#endif
+
+  cl_arg_types[0] = &ffi_type_double;
+  cl_arg_types[1] = NULL;
+
+  /* Initialize the cif */
+  CHECK(ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1,
+		     &ffi_type_double, cl_arg_types) == FFI_OK);
+
+  CHECK(ffi_prep_closure(pcl, &cif, cls_ret_double_fn, NULL)  == FFI_OK);
+
+  res = (*((cls_ret_double)pcl))(21474.789);
+  /* { dg-output "21474.789000: 21474.789000" } */
+  printf("res: %.6f\n", res);
+  /* { dg-output "\nres: 21474.789000" } */
+
+  exit(0);
+}