cmd/compile: regenerate known formats for TestFormats

This fixes the build for long-running tests after CL 139338

Change-Id: Ib8adfa785d41c736188e2ff7e14125de045b96b9
Reviewed-on: https://go-review.googlesource.com/c/139637
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/fmt_test.go

@@ -583,7 +583,6 @@ var knownFormats = map[string]string{
 	"*cmd/compile/internal/ssa.sparseTreeMapEntry %v": "",
 	"*cmd/compile/internal/types.Field %p":            "",
 	"*cmd/compile/internal/types.Field %v":            "",
-	"*cmd/compile/internal/types.Sym %+v":             "",
 	"*cmd/compile/internal/types.Sym %0S":             "",
 	"*cmd/compile/internal/types.Sym %S":              "",
 	"*cmd/compile/internal/types.Sym %p":              "",