(By "vet lite", we mean static tools that must be invoked by a build
system, such as 'go vet'.)
This CL publishes the former internal/unitchecker package.
Its misnamed Main function is renamed Run, and it has a new Main
that does the steps of a real main (log, flag, etc).
The motivation for this change is to reduce cmd/vet-lite to the point
of triviality to simplify the maintenance of the vendored copy of
x/tools in GOROOT, because GOROOT/src/cmd/vet will need a copy of that
logic. It is now essentially a one-liner.
Also, improve usage messages; analysisflags.PrintUsage wasn't
appropriate for all callers so it has been eliminated.
Each of {single,multi,unit}checker prints its own 1-line usage message.
Change-Id: I214c0e4ae7a2923eee8df3f7548341f2320cad2b
Reviewed-on: https://go-review.googlesource.com/c/149742
Reviewed-by: Michael Matloob <matloob@golang.org>
17409aa234