lang/gnatdroid-*: Support multiple API, base on gcc-aux (gcc 4.9)
This represents major changes with gnatdroid.
The sysroot is no longer API 9 or 19, but a choice of API 8, 9, 15,
16, 17, 18, or 19. The prefix is not androidX but just "android".
The binutils port had to be adjusted due to the prefix change.
Finally, gnatdroid-armv(5,7) was substancially reworked to use
gcc-aux (4.9) instead of gcc47-aux (4.7). This means the new ARM
unwinder is in use (zero cost exceptions). Only 6 ACATS tests are
failing, they are related to the missing stack check capability.
Future work will speed up ACATS remote device testing and hopefully
enable gnat.dg testing too.