This makes the distinction between what the bootstrap .ninja file and
the main .ninja files do clearer: the bootstrap .ninja file includes the
build-globs.ninja file(s) which the main .ninja file writes.
This required removing the "default" statement from said bootstrap
.ninja file: now we can build more than one thing instead of just
build.ninja and thus soong_ui explicitly tells Ninja what to do instead.
On the side, stop catering for the use case where the bootstrap
Blueprint invocation uses globs: Soong's does not and that's our only
use case.
Test: Presubmits.
Change-Id: Icffce31928242cfe9cdab56b290a37598d32a58c
d3a0637702