fixed warnings cause by common compiler options

ftpd.c (trim trailing spaces)
vfs.c (added suggested parentheses)
fixed prototype of main() function

test-in-docker/src/main.c

@@ -120,7 +120,7 @@ static err_t init_callback(struct netif* netif) {
 	return ERR_OK;
 }
 
-int main(size_t argc, char **argv) {
+int main(int argc, char **argv) {
 	pcap_t *pcap = pcap_open_live("eth0", 65536, 1, 100, NULL);
 	char errbuf[PCAP_ERRBUF_SIZE];
 	int r = pcap_setnonblock(pcap, 1, errbuf);

vfs.c

@@ -74,7 +74,7 @@ int vfs_stat(vfs_t* vfs, const char* filename, vfs_stat_t* st) {
 		.tm_hour = (f.ftime >> 11) & 0x1f,
 		.tm_mday = f.fdate & 0x1f,
 		.tm_mon = (f.fdate >> 5) & 0xf,
-		.tm_year = 80 + (f.fdate >> 9) & 0x7f,
+		.tm_year = 80 + ((f.fdate >> 9) & 0x7f),
 	};
 	st->st_mtime = mktime(&tm);
 	return 0;