runtime: correct reference to getStackMap in comment

Change-Id: I9b1fa390434dbda7d49a36b0114c68f942c11d3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/707575
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: ianlancetaylor

src/runtime/traceback.go

@@ -429,7 +429,7 @@ func (u *unwinder) resolveInternal(innermost, isSyscall bool) {
 			// gp._defer for a defer corresponding to this function, but that
 			// is hard to do with defer records on the stack during a stack copy.)
 			// Note: the +1 is to offset the -1 that
-			// stack.go:getStackMap does to back up a return
+			// (*stkframe).getStackMap does to back up a return
 			// address make sure the pc is in the CALL instruction.
 		} else {
 			frame.continpc = 0