SPARC architecture specific patch. Probably cannot send upstream.  

--- comm-esr31/mozilla/js/src/ctypes/libffi/src/closures.c.orig	2015-05-07 22:39:07.816379536 +0530
+++ comm-esr31/mozilla/js/src/ctypes/libffi/src/closures.c	2015-05-07 22:39:42.088095728 +0530
@@ -608,3 +608,12 @@ ffi_closure_free (void *ptr)
 
 # endif /* ! FFI_MMAP_EXEC_WRIT */
 #endif /* FFI_CLOSURES */
+
+#ifdef __sparc
+#include <strings.h>
+int
+__ffssi2 (int x)
+{
+ffs (x);
+}
+#endif