Include <arpa/inet.h> for inet_addr and inet_ntop.  . Include
<netax25/axlib.h> for ax25_aton_entry.  Replace implicit ints with
explicit ints.

This changes avoid build failures with future compilers.

Submitted upstream: <https://github.com/n2ygk/aprsdigi/pull/11>

diff --git a/aprsdigi.c b/aprsdigi.c
index c75c8fce7cb79853..23869e889c29c2ec 100644
--- a/aprsdigi.c
+++ b/aprsdigi.c
@@ -45,6 +45,7 @@ static char copyr[] = "Copyright (c) 1996,1997,1999,2001,2002,2003,2004,2009,201
 #include <sys/un.h>
 #include <net/if.h>
 #include <netinet/if_ether.h>
+#include <arpa/inet.h>
 #include <netinet/in.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
diff --git a/fiforead.c b/fiforead.c
index 87e1549e8a1e734a..14db7d6eacd6cfeb 100644
--- a/fiforead.c
+++ b/fiforead.c
@@ -20,6 +20,7 @@ int Verbose = 1;
 
 static void die(char *s);
 
+int
 main(int argc, char **argv)
 {
   struct sockaddr_un mysun,remsun;
diff --git a/fifowrite.c b/fifowrite.c
index b72c0c6072e80e4e..e0a4ddd8a32c2b64 100644
--- a/fifowrite.c
+++ b/fifowrite.c
@@ -20,6 +20,7 @@ int Verbose = 1;
 
 static void die(char *s);
 
+int
 main(int argc, char **argv)
 {
   struct sockaddr_un mysun;
diff --git a/testmcast.c b/testmcast.c
index f7e65a57e8866ce9..b11cfae381227f7c 100644
--- a/testmcast.c
+++ b/testmcast.c
@@ -6,6 +6,7 @@
 #include <sys/socket.h>
 #include <net/if.h>
 #include <netinet/if_ether.h>
+#include <arpa/inet.h>
 #include <netinet/in.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
@@ -33,6 +34,7 @@ die(char *p, char *s)
   exit(1);
 }
 
+int
 main(int argc,char **argv)
 {
   struct sockaddr_in sin;
diff --git a/testparse.c b/testparse.c
index 0bf471f73e79fcbb..36fcf3db7bc0b9ff 100644
--- a/testparse.c
+++ b/testparse.c
@@ -27,7 +27,8 @@ static void print_it(FILE *f,
 	      int len);
 static void drop_unused_digis(struct ax_calls *);
 
-main()
+int
+main(void)
 {
   unsigned char buf[2048],*bp;
   int buflen, *lp = &buflen;