fix the compile error of powerpc64
 
Upstream-status: Accepted

 fix the following error
 |error: 'jsuword' does not name a type


--- a/js/src/jsval.hold	2015-04-24 01:15:06.692970731 -0500
+++ b/js/src/jsval.h	2015-04-24 01:15:41.792969478 -0500
@@ -304,7 +304,6 @@
             int32_t        i32;
             uint32_t       u32;
             JSWhyMagic     why;
-            jsuword        word;
         } payload;
     } s;
     double asDouble;