Currently building SRILM for 64-bit development for armv8 using NDK r20
and clang.

Formerly built both 32-bit and 64-bit using NDK r11c and gcc.

The current setup almost certainly breaks the 32-bit build for armv7.

The last known good 32-bit build is in
common/Makefile.core.android.r11c, last built using NDK r11c.

To use this, copy Makefile.core.android.r11c to Makefile.core.android.

There is a build configuration for NDK r16b to be found in
Makefile.core.android.r16b, this is not tested so use at your own risk.