Switch mips64 back to NDK r10.

The NDK doesn't support mips32r6, and the update of prebuilts/ndk to
r11 doesn't have the hack that r10 did. Revert back to r10, until we
decide on a more appropriate solution.

Change-Id: I7891603d8ccbb20398aad893b62c1debf353ef41
1 file changed