t/helper: don't depend on implicit wraparound

In our test helpers we have two cases where we assign -1 to an `unsigned
long`. The intent is to essentially mean "unbounded output", which is
achieved via implicit wraparound of the value.

This pattern causes warnings with -Wsign-compare though. Adapt it and
instead use `ULONG_MAX` explicitly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

t/helper/test-csprng.c

@@ -1,9 +1,6 @@
-#define DISABLE_SIGN_COMPARE_WARNINGS
-
 #include "test-tool.h"
 #include "git-compat-util.h"
 
-
 int cmd__csprng(int argc, const char **argv)
 {
 	unsigned long count;
@@ -14,7 +11,7 @@ int cmd__csprng(int argc, const char **argv)
 		return 2;
 	}
 
-	count = (argc == 2) ? strtoul(argv[1], NULL, 0) : -1L;
+	count = (argc == 2) ? strtoul(argv[1], NULL, 0) : ULONG_MAX;
 
 	while (count) {
 		unsigned long chunk = count < sizeof(buf) ? count : sizeof(buf);

t/helper/test-genrandom.c

@@ -4,8 +4,6 @@
  * Copyright (C) 2007 by Nicolas Pitre, licensed under the GPL version 2.
  */
 
-#define DISABLE_SIGN_COMPARE_WARNINGS
-
 #include "test-tool.h"
 #include "git-compat-util.h"
 
@@ -24,7 +22,7 @@ int cmd__genrandom(int argc, const char **argv)
 		next = next * 11 + *c;
 	} while (*c++);
 
-	count = (argc == 3) ? strtoul(argv[2], NULL, 0) : -1L;
+	count = (argc == 3) ? strtoul(argv[2], NULL, 0) : ULONG_MAX;
 
 	while (count--) {
 		next = next * 1103515245 + 12345;