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
Everything can be broken out into modules now, so there's not need to
keep the whole world in one file. This also brings us to the point
where we no longer require changes to any files in test/ compared to
upstream, only new files.
Change-Id: I3da27e12e6e2890355013c51567415436c4b517b