cmd/go: added missing space to pkg-config errors
pkg-config errors were missing a space between pkg-config flags and packages
e.g. pkg-config --cflags --staticsdl2
Fixes #25260
Change-Id: Iacecb697c5782c4822db9eefa1a2e4c4daf91a69
GitHub-Last-Rev:
2adf8576be66e31160c109a79f3853feac293f1b
GitHub-Pull-Request: golang/go#25261
Reviewed-on: https://go-review.googlesource.com/111638
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>