cmd/preprofile: Add preprocess tool to pre-parse the profile file.
The pgo compilation time is very long if the profile file is large.
We added a preprocess tool to pre-parse profile file in order to
expedite the compile time.
Change-Id: I6f50bbd01f242448e2463607a9b63483c6ca9a12
Reviewed-on: https://go-review.googlesource.com/c/go/+/529738 Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com>