MSVC: fix t0040-parse-options crash

On 64-bit MSVC, pointers are 64 bit but `long` is only 32.
Thus, casting string to `unsigned long`, which is redundand on other
platforms, throws away important bits and when later cast to `intptr_t`
results in corrupt pointer.

This patch fixes test-parse-options by replacing harming cast with
correct one.

Signed-off-by: Marat Radchenko <marat@slonopotamus.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

test-parse-options.c

@@ -60,7 +60,7 @@ int main(int argc, char **argv)
 		OPT_STRING('o', NULL, &string, "str", "get another string"),
 		OPT_NOOP_NOARG(0, "obsolete"),
 		OPT_SET_PTR(0, "default-string", &string,
-			"set string to default", (unsigned long)"default"),
+			"set string to default", (intptr_t)"default"),
 		OPT_STRING_LIST(0, "list", &list, "str", "add str to list"),
 		OPT_GROUP("Magic arguments"),
 		OPT_ARGUMENT("quux", "means --quux"),