Merge from widevine repo of http://go/wvgerrit/17223
This CL turns off the mips64 bit build for widevine. This is because
the level 3 mips32 library does not build and run correctly for a 64
bit target.
b/27786231
Change-Id: I3388d9ebc80ae3cf477a8a54adfd1f22dfac4dda