Do not install transitive packaging specs of overriden modules

e.g. if a cc_binary is overriden, its shared_libs should not be
installed.

To do, a new `depNames` array is introduced to track the top-level
module which requested the packaging spec. If the top-level module has
been overridden, the packaging spec will not be installed.

Test: go test ./filesystem
Test: vendor partition diffs for aosp cf https://diff.googleplex.com/#key=276Je74QO1VE
Change-Id: I1c8df831c696990bb0982e4537129b8e85abeda6