cmd/compile: fix message typo

occurences -> occurrences

Change-Id: Ia81671f5de8a24ddd303a77b4580e8c726f29122
GitHub-Last-Rev: 11f9ab9
GitHub-Pull-Request: #43097
Reviewed-on: https://go-review.googlesource.com/c/go/+/276612
Reviewed-by: Robert Griesemer <[email protected]>
Reviewed-by: Keith Randall <[email protected]>

Author: Ikko Ashimine

src/cmd/compile/internal/logopt/logopt_test.go

@@ -51,7 +51,7 @@ func want(t *testing.T, out string, desired string) {
 
 func wantN(t *testing.T, out string, desired string, n int) {
 	if strings.Count(out, desired) != n {
-		t.Errorf("expected exactly %d occurences of %s in \n%s", n, desired, out)
+		t.Errorf("expected exactly %d occurrences of %s in \n%s", n, desired, out)
 	}
 }