[ARC/LIBGCC] Add TLS support.

libgcc/
2016-04-28  Claudiu Zissulescu  <claziss@synopsys.com>
	    Joern Rennecke  <joern.rennecke@embecosm.com>

	* config/arc/crttls.S: New file.
	* config/arc/t-arc: New rule.
	* config.host (arc*-*-elf*, arc*-*-linux*): Add crttls.o.

Co-Authored-By: Joern Rennecke <joern.rennecke@embecosm.com>

From-SVN: r235558