runtime/cgo: retry _beginthread on EACCES

We occassionally see _beginthread failing with EACCES, meaning
"insufficient resources" according to the Microsoft documentation.
Exactly which resources is unclear.

Similar to pthread_create on unix systems, we can wait a bit and retry
to try to get success. The alternative is to abort, so we may as well
give it a try.

Fixes #52572.

Change-Id: I6e05add53b4ae36c61e53b1ee3fed6bc74e17dfa
Reviewed-on: https://go-review.googlesource.com/c/go/+/410355
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/runtime/cgo/gcc_libinit_windows.c

@@ -129,11 +129,23 @@ void (*(_cgo_get_context_function(void)))(struct context_arg*) {
 }
 
 void _cgo_beginthread(void (*func)(void*), void* arg) {
+	int tries;
 	uintptr_t thandle;
 
-	thandle = _beginthread(func, 0, arg);
-	if (thandle == -1) {
-		fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
-		abort();
+	for (tries = 0; tries < 20; tries++) {
+		thandle = _beginthread(func, 0, arg);
+		if (thandle == -1 && errno == EACCES) {
+			// "Insufficient resources", try again in a bit.
+			//
+			// Note that the first Sleep(0) is a yield.
+			Sleep(tries); // milliseconds
+			continue;
+		} else if (thandle == -1) {
+			break;
+		}
+		return; // Success!
 	}
+
+	fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
+	abort();
 }