Fix allocation size in vaswprintf

This is so embarrassing. It only started crashing once it had strings
that were long enough, and then it took me so long to notice this
mistake. I was worried I was still doing va_list wrong somehow.

pls.c

@@ -47,7 +47,7 @@ int vaswprintf(wchar_t **ret, const wchar_t *format, va_list ap) {
 	*ret = NULL;
 
 	for (size_t cap = 2 * wcslen(format);; cap *= 2) {
-		wchar_t *buf = realloc(*ret, 1 + cap);
+		wchar_t *buf = realloc(*ret, sizeof(*buf) * (1 + cap));
 		if (!buf) goto fail;
 		*ret = buf;