Make libbnnmlowp buildable for native_bridge am: ebffc28dbb am: 3c25e3c4f7 am: 7420449dd2

Original change: https://android-review.googlesource.com/c/platform/external/gemmlowp/+/1328959

Change-Id: I2ae3b21e9e71c2db341fdb6c81d5572a73939f39