Bug 570334: Support a CPU_ARCH of x86_64, which is set by mingw-w64.  The patch is contributed by Jacek Caban <jacek@codeweavers.com>.  r=wtc.
Bug 570334: Support a CPU_ARCH of x86_64, which is set by mingw-w64.  The
patch is contributed by Jacek Caban <jacek@codeweavers.com>.  r=wtc.

nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,nmav/nss,nmav/nss,nmav/nss,ekr/nss-old,ekr/nss-old,ekr/nss-old