[release-branch.go1.19] runtime: allow for 5 more threads in TestWindowsStackMemory*

Original version of TestWindowsStackMemory did not consider sysmon and
other threads running during the test. Allow for 5 extra threads in this
test - this should cover any new threads in the future.

For #58570
Fixes #61054

Change-Id: I215790f9b94ff40a32ddd7aa54af715d1dc391c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/473415
Reviewed-by: Michael Pratt <[email protected]>
Run-TryBot: Alex Brainman <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
(cherry picked from commit f6cbc1d)
Reviewed-on: https://go-review.googlesource.com/c/go/+/506975
Run-TryBot: Michael Knyszek <[email protected]>
Auto-Submit: Michael Knyszek <[email protected]>
(cherry picked from commit 08a58dd)
Reviewed-on: https://go-review.googlesource.com/c/go/+/506976
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: alexbrainman

src/runtime/testdata/testprog/syscall_windows.go

@@ -66,5 +66,8 @@ func StackMemory() {
 	if err != nil {
 		panic(err)
 	}
-	print((mem2 - mem1) / threadCount)
+	// assumes that this process creates 1 thread for each
+	// thread locked goroutine plus extra 5 threads
+	// like sysmon and others
+	print((mem2 - mem1) / (threadCount + 5))
 }

src/runtime/testdata/testprogcgo/stack_windows.go

@@ -50,5 +50,8 @@ func StackMemory() {
 	if err != nil {
 		panic(err)
 	}
-	print((mem2 - mem1) / threadCount)
+	// assumes that this process creates 1 thread for each
+	// thread locked goroutine plus extra 5 threads
+	// like sysmon and others
+	print((mem2 - mem1) / (threadCount + 5))
 }