Recent changes in detecting big endian targets don't work when cross
compiling for a target with different endianness. This brakes MIPS.
Added additional checks for big endian MIPS and MIPS64 targets to fix
this.

Patch by miran.karic@imgtec.com

BUG=None
R=bjaideep@ca.ibm.com, jshin@chromium.org

Review URL: https://codereview.chromium.org/2518533002 .