Fix the compile errors I got

- void out link variable in non-unix to prevent unused variable error
- change n's type to size_t from int to prevent unsigned signed comparison

src/sdl/i_main.c

@@ -213,6 +213,7 @@ int main(int argc, char **argv)
 			I_OutputMsg("Error symlinking latest-log.txt: %s\n", strerror(errno));
 		}
 #else/*__unix__*/
+		(void)link;
 		logstream = fopen("latest-log.txt", "wt+");
 #endif/*__unix__*/
 	}

src/sdl/i_system.c

@@ -3282,7 +3282,7 @@ static void Shittylogcopy(void)
 {
 	char buf[8192];
 	FILE *fp;
-	int n;
+	size_t n;
 	if (fseek(logstream, 0, SEEK_SET) == -1)
 	{
 		Shittycopyerror("fseek");