Include arpa/inet.h instead of sys/endian.h

The header is included to get defintion for htons. In termux the
definition is in sys/endian.h, but on other systems it is in
arpa/inet.h.

arpa/inet.h includes sys/endian.h though, so including that header
works in termux as well.

Change to arpa/inet.h so that termux-api-package can be easily
compiled both in termux and for other systems.

Author: Grimler91

termux-api.c

@@ -8,7 +8,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/endian.h>
+#include <arpa/inet.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>