Index: lang/spidermonkey170/files/patch-jsval.h
===================================================================
--- /dev/null
+++ lang/spidermonkey170/files/patch-jsval.h
@@ -0,0 +1,19 @@
+Fix build on 64-bit big-endian machines.
+
+The jsuword type does not exist (which causes the build to break).
+Trying to define "word" as size_t triggers a static assertion due to
+jsval_layout growing too big.
+
+Therefore, do as the 64-bit little endian code path and just avoid
+defining the "word" field.  Tested on ppc64.
+
+--- js/src/jsval.h.orig	2015-08-15 10:28:43.716780000 -0400
++++ js/src/jsval.h	2015-08-16 22:54:21.456094000 -0400
+@@ -304,7 +304,6 @@ typedef union jsval_layout
+             int32_t        i32;
+             uint32_t       u32;
+             JSWhyMagic     why;
+-            jsuword        word;
+         } payload;
+     } s;
+     double asDouble;