split inet_addr and inet_ntoa back into their own files

despite being practically deprecated, these functions are still part
of the standard and thus cannot reside in a file that also contains
namespace pollution. this reverts some of the changes made in commit
e40f48a4.

src/network/inet_addr.c

+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include "__dns.h"
+
+in_addr_t inet_addr(const char *p)
+{
+	struct sockaddr_in sin;
+	if (__ipparse(&sin, AF_INET, p)) return -1;
+	return sin.sin_addr.s_addr;
+}

src/network/inet_legacy.c

 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
-#include <stdio.h>
 #include "__dns.h"
 
-in_addr_t inet_addr(const char *p)
-{
-	struct sockaddr_in sin;
-	if (__ipparse(&sin, AF_INET, p)) return -1;
-	return sin.sin_addr.s_addr;
-}
-
 in_addr_t inet_network(const char *p)
 {
 	return ntohl(inet_addr(p));
@@ -21,14 +13,6 @@ int inet_aton(const char *cp, struct in_addr *inp)
 	return inet_pton(AF_INET, cp, (void *)inp) > 0;
 }
 
-char *inet_ntoa(struct in_addr in)
-{
-	static char buf[16];
-	unsigned char *a = (void *)&in;
-	snprintf(buf, sizeof buf, "%d.%d.%d.%d", a[0], a[1], a[2], a[3]);
-	return buf;
-}
-
 struct in_addr inet_makeaddr(int net, int host)
 {
 	uint32_t n = net, h = host;

src/network/inet_ntoa.c

+#include <arpa/inet.h>
+#include <stdio.h>
+
+char *inet_ntoa(struct in_addr in)
+{
+	static char buf[16];
+	unsigned char *a = (void *)&in;
+	snprintf(buf, sizeof buf, "%d.%d.%d.%d", a[0], a[1], a[2], a[3]);
+	return buf;
+}