gotest: don't use local

It's not part of the POSIX shell standard.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/214300

From-SVN: r280118

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-98c4c21b52afd6384f9364527bd7f5f9a1c752cf
+a69ad9c7d1b45edcf8062a07d3a3c9b6838c04f8
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/testsuite/gotest

@@ -538,8 +538,7 @@ symtogo() {
 # Takes an example name and puts any output into the file example.txt.
 # It strips comment markers but does not otherwise change the output.
 exampleoutput() {
-    local n=$(testname $1)
-    local f
+    n=$(testname $1)
     for f in $gofiles $xgofiles; do
 	if ! grep "^func $n(" $f >/dev/null 2>&1; then
 	    continue