Metrics are added to a materialized protobuf soong_build_metrics.pb
Recorded events have scoped names and recorded runtimes.
For example, mixedbuilds includes the following events:
mixedbuilds.prepare
mixedbuilds.analyze.write_files
mixedbuild (this is a total of all mixedbuild events)
Test: Manually verified materialized protos for mixedbuild, bp2build,
and legacy build.
Change-Id: I2e72d4502c0373bee0279bb1320b2e4dd586129c
Major operations:
* Fix the go_package entries to be consistent, as the new tool
complains when it doesn't have a '/'.
* Regenerate with the new protoc-gen-go tool.
* github.com/golang/protobuf -> google.golang.org/protobuf
* proto.[Un]MarshalText -> prototext.[Un]Marshal
Change-Id: Ie1147bd2457fafb66ba555461b3bf14f0561a25d
Collect the number of modules and variants and some basic statistics
on memory usage inside soong_build by writing out a proto that is
read back in by soong_ui.
Test: examine soong.log
Change-Id: I6926876377a4f6229cf41fdbf166ae03c885ea55
