git-compat-util.h: Provide missing netdb.h definitions

Some platforms may lack the NI_MAXHOST and NI_MAXSERV values in their
system headers, so ensure they are available.

Signed-off-by: David Michael <fedora.dm0@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-compat-util.h b/git-compat-util.h
index 000042d..503282c 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -178,6 +178,17 @@
 #include <openssl/err.h>
 #endif
 
+/* On most systems <netdb.h> would have given us this, but
+ * not on some systems (e.g. z/OS).
+ */
+#ifndef NI_MAXHOST
+#define NI_MAXHOST 1025
+#endif
+
+#ifndef NI_MAXSERV
+#define NI_MAXSERV 32
+#endif
+
 /* On most systems <limits.h> would have given us this, but
  * not on some systems (e.g. GNU/Hurd).
  */