More fixes for libpq's .gitignore file.

The previous patches failed to cover a lot of symlinks that are only
added in platform-specific cases.  Make the lists match what's in the
Makefile for each branch.

src/interfaces/libpq/.gitignore

@@ -1,11 +1,12 @@
-/encnames.c
-/exports.list
-/ip.c
-/md5.c
-/noblock.c
-/pgstrcasecmp.c
-/strlcpy.c
-/thread.c
-/wchar.c
-/dllist.c
+/crypt.c
+/getaddrinfo.c
+/inet_aton.c
+/snprintf.c
+/strerror.c
 /path.c
+/thread.c
+/md5.c
+/ip.c
+/dllist.c
+/encnames.c
+/wchar.c