Move <rpc/netdb.h> from sunrpc to inet

Restore <rpc/netdb.h> as an installed header. Delete the dummy header
resolv/rpc/netdb.h because inet is not an optional glibc component
(so its <rpc/netdb.h> is always available).

Fixes commit acb527929d ("Move
non-deprecated RPC-related functions from sunrpc to inet") in
combination with commit 5500cdba40
("Remove --enable-obsolete-rpc configure flag").

include/rpc/netdb.h

@@ -1,5 +1,5 @@
 #ifndef _RPC_NETDB_H
-#include <sunrpc/rpc/netdb.h>
+#include <inet/rpc/netdb.h>
 
 # ifndef _ISOMAC
 

inet/Makefile

@@ -25,7 +25,8 @@ include ../Makeconfig
 headers	:= netinet/ether.h netinet/in.h netinet/in_systm.h \
 	   netinet/if_ether.h netinet/igmp.h \
 	   netinet/tcp.h netinet/ip.h $(wildcard arpa/*.h protocols/*.h) \
-	   aliases.h ifaddrs.h netinet/ip6.h netinet/icmp6.h bits/in.h
+	   aliases.h ifaddrs.h netinet/ip6.h netinet/icmp6.h bits/in.h \
+	   rpc/netdb.h
 
 routines := htonl htons		\
 	    inet_lnaof inet_mkadr	\

resolv/Makefile

@@ -126,13 +126,6 @@ tests-special += $(objpfx)mtrace-tst-resolv-res_ninit.out
 endif
 endif
 
-ifeq (,$(filter sunrpc,$(subdirs)))
-# The netdb.h we install does '#include <rpc/netdb.h>', so one must exist.
-# If sunrpc/ is built in this configuration, it installs a real <rpc/netdb.h>.
-# If that's not going to happen, install our dummy file.
-headers += rpc/netdb.h
-endif
-
 generated += mtrace-tst-leaks.out tst-leaks.mtrace \
 	     mtrace-tst-leaks2.out tst-leaks2.mtrace \
 	     mtrace-tst-resolv-res_ninit.out tst-resolv-res_ninit.mtrace \

resolv/rpc/netdb.h

@@ -1,3 +0,0 @@
-/* This is a dummy file for <rpc/netdb.h>, which is included by <netdb.h>.
-   This file is installed when the C library does not support the SunRPC
-   interfaces (including 'struct rpcent' et al) at all.  */