all_modules would trigger all Soong modules to be built and installed.
Bug: 30191725
Test: Ran external/libcxx/run-tests.py, appears to build properly
Change-Id: I11ff39c5681c4b07b8b6456b7302531e4e746e15
Invoking these from make was pretty gross, and apparently I was
getting it wrong for the buildbot (was running mmm buildcmds without
running configtests).
This makes a single entry point of run-tests.py. The ugly hacks for
cflags/ldflags detection is still there, but it's at least not *as*
bad.
Change-Id: I0157700d83f6a38a209751a03a00dc9a8e708744