Fix compilation for mingw32 and cygwin

inet_pton is available only in windows vista or later,
fixed the issue by reimplementing it using WSAStringToAddress

src/netops.c

@@ -274,11 +274,11 @@ static int verify_server_cert(gitno_ssl *ssl, const char *host)
 	}
 
 	/* Try to parse the host as an IP address to see if it is */
-	if (inet_pton(AF_INET, host, &addr4)) {
+	if (gitno_inet_pton(AF_INET, host, &addr4)) {
 		type = GEN_IPADD;
 		addr = &addr4;
 	} else {
-		if(inet_pton(AF_INET6, host, &addr6)) {
+		if(gitno_inet_pton(AF_INET6, host, &addr6)) {
 			type = GEN_IPADD;
 			addr = &addr6;
 		}
@@ -597,3 +597,51 @@ int gitno_extract_host_and_port(char **host, char **port, const char *url, const
 
 	return 0;
 }
+
+int gitno_inet_pton(int af, const char* src, void* dst)
+{
+	/* inet_pton is only available in Windows Vista or later
+	 * mingw32 and cygwin give compile errors */
+#ifndef GIT_WIN32
+	return inet_pton(af, src, dst);
+#else
+	union {
+		struct sockaddr_in6 sin6;
+		struct sockaddr_in sin;
+	} sa;
+	size_t srcsize;
+
+	switch(af)
+	{
+		case AF_INET:
+			sa.sin.sin_family = AF_INET;
+			srcsize = sizeof (sa.sin);
+		break;
+		case AF_INET6:
+			sa.sin6.sin6_family = AF_INET6;
+			srcsize = sizeof (sa.sin6);
+		break;
+		default:
+			errno = WSAEPFNOSUPPORT;
+			return -1;
+	}
+
+	if (WSAStringToAddress(src, af, NULL, (struct sockaddr *) &sa, &srcsize) != 0)
+	{
+		errno = WSAGetLastError();
+		return -1;
+	}
+
+	switch(af)
+	{
+		case AF_INET:
+			memcpy(dst, &sa.sin.sin_addr, sizeof(sa.sin.sin_addr));
+		break;
+		case AF_INET6:
+			memcpy(dst, &sa.sin6.sin6_addr, sizeof(sa.sin6.sin6_addr));
+		break;
+	}
+
+	return 1;
+#endif
+}

src/netops.h

@@ -67,5 +67,6 @@ int gitno_close(gitno_socket *s);
 int gitno_select_in(gitno_buffer *buf, long int sec, long int usec);
 
 int gitno_extract_host_and_port(char **host, char **port, const char *url, const char *default_port);
+int gitno_inet_pton(int af, const char *src, void *dst);
 
 #endif