Each variable can specify a conditions_default for properties to be used
when the variable is not set, not set to a true value (for bools), or is
set to a value that is not present in the module (for strings).
Test: m nothing
Test: go test soong tests
Change-Id: I76ec026da2369b407f0f530f77760f530e7958fc
Give prebuilt_etc and sh_binary their own packages and split the
gigantic main Android.bp up to small, per-package ones.
Test: m nothing, TreeHugger
Bug: 156980228
Change-Id: I7b00cd344b9f16861f1ff39edf0029f016b853d0
