Convert genxml to Android.bp

This is a header library (was a static library with a dummy .o file)
that exports a number of prebuilt and generated header files.

Bug: 122332854
Test: mmm external/mesa3d
Test: treehugger
Change-Id: Iec37aedb1dd46977d1b1c7a53b38d7cf201012bc
10 files changed