Move code shared between libpq and backend from backend/libpq/ to common/.

When building libpq, ip.c and md5.c were symlinked or copied from
src/backend/libpq into src/interfaces/libpq, but now that we have a
directory specifically for routines that are shared between the server and
client binaries, src/common/, move them there.

Some routines in ip.c were only used in the backend. Keep those in
src/backend/libpq, but rename to ifaddr.c to avoid confusion with the file
that's now in common.

Fix the comment in src/common/Makefile to reflect how libpq actually links
those files.

There are two more files that libpq symlinks directly from src/backend:
encnames.c and wchar.c. I don't feel compelled to move those right now,
though.

Patch by Michael Paquier, with some changes by me.

Discussion: <69938195-9c76-8523-0af8-eb718ea5b36e@iki.fi>

3 files changed, 30 insertions, 81 deletions

diff --git a/src/include/libpq/ifaddr.h b/src/include/libpq/ifaddr.h
new file mode 100644
index 0000000000..40094a612a
--- /dev/null
+++ b/src/include/libpq/ifaddr.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * ifaddr.h
+ *	  IP netmask calculations, and enumerating network interfaces.
+ *
+ * Copyright (c) 2003-2016, PostgreSQL Global Development Group
+ *
+ * src/include/libpq/ifaddr.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef IFADDR_H
+#define IFADDR_H
+
+#include "libpq/pqcomm.h"		/* pgrminclude ignore */
+
+typedef void (*PgIfAddrCallback) (struct sockaddr * addr,
+											  struct sockaddr * netmask,
+											  void *cb_data);
+
+extern int pg_range_sockaddr(const struct sockaddr_storage * addr,
+				  const struct sockaddr_storage * netaddr,
+				  const struct sockaddr_storage * netmask);
+
+extern int pg_sockaddr_cidr_mask(struct sockaddr_storage * mask,
+					  char *numbits, int family);
+
+extern int	pg_foreach_ifaddr(PgIfAddrCallback callback, void *cb_data);
+
+#endif   /* IFADDR_H */
diff --git a/src/include/libpq/ip.h b/src/include/libpq/ip.h
deleted file mode 100644
index ce9bc6e225..0000000000
--- a/src/include/libpq/ip.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * ip.h
- *	  Definitions for IPv6-aware network access.
- *
- * These definitions are used by both frontend and backend code.  Be careful
- * what you include here!
- *
- * Copyright (c) 2003-2016, PostgreSQL Global Development Group
- *
- * src/include/libpq/ip.h
- *
- *-------------------------------------------------------------------------
- */
-#ifndef IP_H
-#define IP_H
-
-#include "getaddrinfo.h"		/* pgrminclude ignore */
-#include "libpq/pqcomm.h"		/* pgrminclude ignore */
-
-
-#ifdef	HAVE_UNIX_SOCKETS
-#define IS_AF_UNIX(fam) ((fam) == AF_UNIX)
-#else
-#define IS_AF_UNIX(fam) (0)
-#endif
-
-typedef void (*PgIfAddrCallback) (struct sockaddr * addr,
-											  struct sockaddr * netmask,
-											  void *cb_data);
-
-extern int pg_getaddrinfo_all(const char *hostname, const char *servname,
-				   const struct addrinfo * hintp,
-				   struct addrinfo ** result);
-extern void pg_freeaddrinfo_all(int hint_ai_family, struct addrinfo * ai);
-
-extern int pg_getnameinfo_all(const struct sockaddr_storage * addr, int salen,
-				   char *node, int nodelen,
-				   char *service, int servicelen,
-				   int flags);
-
-extern int pg_range_sockaddr(const struct sockaddr_storage * addr,
-				  const struct sockaddr_storage * netaddr,
-				  const struct sockaddr_storage * netmask);
-
-extern int pg_sockaddr_cidr_mask(struct sockaddr_storage * mask,
-					  char *numbits, int family);
-
-extern int	pg_foreach_ifaddr(PgIfAddrCallback callback, void *cb_data);
-
-#endif   /* IP_H */
diff --git a/src/include/libpq/md5.h b/src/include/libpq/md5.h
deleted file mode 100644
index f3eec8b4f4..0000000000
--- a/src/include/libpq/md5.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * md5.h
- *	  Interface to libpq/md5.c
- *
- * These definitions are needed by both frontend and backend code to work
- * with MD5-encrypted passwords.
- *
- * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * src/include/libpq/md5.h
- *
- *-------------------------------------------------------------------------
- */
-#ifndef PG_MD5_H
-#define PG_MD5_H
-
-#define MD5_PASSWD_LEN	35
-
-#define isMD5(passwd)	(strncmp(passwd, "md5", 3) == 0 && \
-						 strlen(passwd) == MD5_PASSWD_LEN)
-
-
-extern bool pg_md5_hash(const void *buff, size_t len, char *hexsum);
-extern bool pg_md5_binary(const void *buff, size_t len, void *outbuf);
-extern bool pg_md5_encrypt(const char *passwd, const char *salt,
-			   size_t salt_len, char *buf);
-
-#endif