cmd/compile: regenerate known formats in fmtmap_test.go

This fixes TestFormats after CL 198037

Change-Id: I3fb7d667f7c2a1fd88a320482310d33b75e068c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/199777
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/fmtmap_test.go

@@ -160,6 +160,7 @@ var knownFormats = map[string]string{
 	"int64 %v":                                        "",
 	"int64 %x":                                        "",
 	"int8 %d":                                         "",
+	"int8 %v":                                         "",
 	"int8 %x":                                         "",
 	"interface{} %#v":                                 "",
 	"interface{} %T":                                  "",