re PR go/91621 (libgo/mksysinfo.sh: please avoid test ==)

	PR go/91621
    mksysinfo: change test == to test =
    
    Fixes https://gcc.gnu.org/PR91621
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/194569

From-SVN: r275608

gcc/go/gofrontend/MERGE

-556451586b10584e4778694c84b03d0ecbbab150
+2f6dd921a21351e94f55a5365a3176af563b5945
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/mksysinfo.sh

@@ -1123,7 +1123,7 @@ grep '^const _FALLOC_' gen-sysinfo.go |
 # Prefer largefile variant if available.
 # CentOS 5 does not have f_flags, so pull from f_spare.
 statfs=`grep '^type _statfs64 ' gen-sysinfo.go || true`
-if test "$statfs" == ""; then
+if test "$statfs" = ""; then
   statfs=`grep '^type _statfs ' gen-sysinfo.go || true`
 fi
 if ! echo "$statfs" | grep f_flags; then