NBSD libc: fix forgot weak_alias

This patch add a few weak_alias forgotten, so that non-internal
symbols are defined to be used from application.

Modifying only the minix-specific part, this patch needs no update
to minix-port.patch.

lib/nbsd_libc/gen/minix/getdomainname.c

@@ -2,10 +2,15 @@
  *								2 Dec 1994
  */
 #define nil 0
+#include "namespace.h"
 #include <sys/types.h>
 #include <unistd.h>
 #include <string.h>
 
+#ifdef __weak_alias
+__weak_alias(getdomainname, _getdomainname)
+#endif
+
 int getdomainname(char *domain, size_t size)
 {
 	char nodename[256];

lib/nbsd_libc/sys-minix/bind.c

@@ -1,6 +1,10 @@
 #include <sys/cdefs.h>
 #include "namespace.h"
 
+#ifdef __weak_alias
+__weak_alias(bind, _bind)
+#endif
+
 #include <unistd.h>
 #include <stdint.h>
 #include <stdlib.h>

lib/nbsd_libc/sys-minix/chown.c

@@ -5,6 +5,10 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifdef __weak_alias
+__weak_alias(chown, _chown)
+#endif
+
 PUBLIC int chown(const char *name, uid_t owner, gid_t grp)
 {
   message m;