This de-duplicates the two separate build.rs files dealing with proto
compilation. The trunks interface.proto will be exposed under
protos::trunks and the plugin proto will be exposed under protos::plugin.
BUG=none
TEST=cargo check
TEST=cargo check --features tpm
TEST=cargo check --features plugin
TEST=cargo check --features tpm,plugin
TEST=FEATURES=test emerge-nami crosvm
TEST=FEATURES=test USE=crosvm-tpm emerge-nami crosvm
TEST=FEATURES=test USE=crosvm-plugin emerge-nami crosvm
TEST=FEATURES=test USE='crosvm-tpm crosvm-plugin' emerge-nami crosvm
TEST=local kokoro
CQ-DEPEND=CL:1553971
Change-Id: I203b654a38e9d671a508156ae06dfb6f70047c4f
Reviewed-on: https://chromium-review.googlesource.com/1556417
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>