There was one case that did not work:
1) Create dir in root source tree
2) Run "m libc"
The build would fail as it was using the mma logic. A separate
one named BUILD_MODULES was added to allow building specific
modules in any directories using the "m" command.
Bug: b/130049705
Test: unit test cases, ran "m libc" in a tmp directory inside
of the source tree.
Change-Id: I8d23e685a673a311001ee8edd89bd73b662392dd
3928206ecc