cmd/cgo: pass end position info for C function arguments.
Pass information about original end position for c function arguments
processed in pointer checking generated code.
Fixes #42580
Change-Id: Ic8a578168362f0ca6055064dbbea092ad37477a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/269760 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>