cmd/compile: skip TestStmtLines on Plan 9
cmd/compile: skip TestStmtLines on Plan 9

TestStmtLines has been added in CL 102435.
This test is failing on Plan 9 because executables
don't have a DWARF symbol table.

Fixes #25387.

Change-Id: I6ae7cba0e8ad4ab569a29ea8920b7849acfb9846
Reviewed-on: https://go-review.googlesource.com/113115
Run-TryBot: David du Colombier <ec8ae1e6620d4bab5e0e7aa2a6ae41aad63e3708@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: David Chase <ae171625adc8645b8b79b7e405a6da5aba5341e0@google.com>

cloudflare/go,josharian/go,cloudflare/go,cloudflare/go,akutz/go,nawawi/go,cloudflare/go,CAFxX/go,CAFxX/go,josharian/go,nawawi/go,josharian/go,cloudflare/go,cloudflare/go,akutz/go,nawawi/go,cloudflare/go,golang/go,golang/go,golang/go,josharian/go,CAFxX/go,nawawi/go,golang/go,golang/go,nawawi/go,nawawi/go,akutz/go,CAFxX/go,josharian/go,golang/go,nawawi/go,akutz/go,akutz/go,akutz/go,golang/go,nawawi/go,CAFxX/go,akutz/go,CAFxX/go,golang/go,josharian/go,cloudflare/go,josharian/go,akutz/go,CAFxX/go,josharian/go,CAFxX/go