cmd/compile/internal/base: add comma in comment for consistency

Change-Id: I9e2ca7eee50f1a642ae2c7468d0a4ea931cbd33e
GitHub-Last-Rev: 93fabec
GitHub-Pull-Request: #61523
Reviewed-on: https://go-review.googlesource.com/c/go/+/512195
Auto-Submit: Keith Randall <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Keith Randall <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: callthingsoff

src/cmd/compile/internal/base/base.go

@@ -245,7 +245,7 @@ func Compiling(pkgs []string) bool {
 // is done during SSA construction rather than a separate SSA pass,
 // see issue #19054.
 //
-// Third we remove calls to racefuncenter and racefuncexit, for leaf
+// Third, we remove calls to racefuncenter and racefuncexit, for leaf
 // functions without instrumented operations. This is done as part of
 // ssa opt pass via special rule.