Allow BottomUpMutators to run in parallel by calling Parallel() on the
return value of RegisterBottomUpMutator. To avoid locking, moves
updates of global state into a separate goroutine that receives updates
over channels from the mutator goroutines.
Change-Id: Ic59b612da9b406cf59ec44940f0c1dee0c051a51
Catch panics in the build logic in order to provide extra data on when
the panic occurred, for example which module had GenerateBuildActions
called on it.
spliceModules was carefully reallocating the slice if necessary, and
then throwing away the reallocated slice and writing to the too-short
original slice. Fix the bug, and add tests that would have caught it.
Change-Id: Ifc13b2025198b270c97097fd7d28cd36e460c98c
