re PR libgcj/25816 (Configure detects TLS, but glibc does not support it.)

	PR java/25816
	* configure.ac (enable_tls): New enable option.
	(HAVE_AS_TLS): Don't do assembler check if enable_tls set.
	* configure: Regenerate.
	* doc/install.texi (--enable-tls): Document new option.
	(--disable-tls): Ditto.

From-SVN: r110199