Speed up lunch/tapas/etc. shell utility functions.
1. Combined ~10 calls to the make build system to only one.
We added a phony target "dump-many-vars" to the build system to dump
"<var>=<value>" pairs. We then store the pairs as shell variables.
With this cache get_build_var/get_abs_build_var can just return
the shell variables instead of querying the build system.
2. Prune .git when we search for AndroidProduct.mks.
In internal source tree lunch time was reduced from ~15s to ~1.5s.
Bug: 27429759
(cherry picked from commit 08800fd905e70faf01d9392d00ff3f49d99097b7)
Change-Id: I862a0ec3c1aae97c552054dacec133e857042edf
4 files changed
