cmd/compile: update the incorrect assignment of call site offset.
The call site calculation in the previous version is incorrect. For
the PGO preprocess file, the compiler should directly use the call
site offset value. Additionly, this change refactors the preprocess
tool to clean up unused fields including startline, the flat and the
cum.
Change-Id: I7bffed3215d4c016d9a9e4034bfd373bf50ab43f
Reviewed-on: https://go-review.googlesource.com/c/go/+/562795 Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com>