Remove non-add-on Banner files.

Various subdirectories of glibc include Banner files to put some text
in the output of executing libc.so.6, under "Available extensions".

Some of those subdirectories (e.g. crypt) may originally have been
add-ons (and so optional, so a particular glibc build might or might
not have included them), but except for libidn they aren't now (or if
only included in some builds, in the case of soft-fp, the inclusion
depends on the architecture for which glibc is configured rather than
having any glibc configuration for which it's an optional feature),
and it doesn't seem useful for the libc.so.6 output to call out a few
features like that.

This patch removes the non-add-on Banner files, updating contrib.texi
where they noted contributions not otherwise mentioned there.

Tested for x86_64.

	* crypt/Banner: Remove file.
	* nptl/Banner: Likewise.
	* resolv/Banner: Likewise.
	* soft-fp/Banner: Likewise.
	* nptl/Makefile ($(objpfx)banner.h): Remove rule.
	($(objpfx)version.d): Remove dependency on banner.h.
	($(objpfx)version.os): Likewise.
	* nptl/version.c (banner): Do not include banner.h.
	* manual/contrib.texi: Update entries for Richard Henderson, Jakub
	Jelinek and BIND code.

nptl/version.c

@@ -22,8 +22,8 @@
 
 
 static const char banner[] =
-#include "banner.h"
-"Copyright (C) 2017 Free Software Foundation, Inc.\n\
+"Native POSIX Threads Library\n\
+Copyright (C) 2017 Free Software Foundation, Inc.\n\
 This is free software; see the source for copying conditions.\n\
 There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A\n\
 PARTICULAR PURPOSE.\n"