cmd/cgo: match note following error in compiler errors
With current GCC a macro that refers to another macro can report an
error on the macro definition line, with a note on the use.
When cgo is trying to decide which line an error refers to,
it is looking at the uses. So if we see an error on a line that we
don't recognize followed by a note on a line that we do recognize,
treat the note as an error.
Fixes #20125.
Change-Id: I389cd0eb7d56ad2d54bef70e278d9f76c4d36448
Reviewed-on: https://go-review.googlesource.com/44290
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Hiroshi Ioka <hirochachacha@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>