Remove NPTL configure errors based on top-level configure tests.

Remove NPTL configure errors based on top-level configure tests.

sysdeps/nptl/configure.ac has code to give errors if certain tests in
the top-level configure failed.  However, all those failure conditions
also produce errors in the top-level configure, so the errors in the
NPTL configure are completely redundant; this patch removes them.

(As suggested in
<https://sourceware.org/ml/libc-alpha/2015-10/msg00510.html>, I think
the top-level tests in question can be completely removed as
unnecessary given the version tests.  But even without that there is
clearly no point in duplicating code that gives an error if the test
fails.)

Tested for x86_64 (testsuite, and that installed shared libraries are
unchanged by the patch).

	* sysdeps/nptl/configure.ac: Do not give errors based on the
	results of top-level configure tests.
	* sysdeps/nptl/configure: Regenerated.