nios2.c: Include xregex.h.

nios2.c: Include xregex.h.

2017-10-26  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* config/nios2/nios2.c: Include xregex.h.
	(nios2_gprel_sec_regex): New.
	(nios2_option_overide): Initialize it.  Don't allow GP-relative
	addressing with PIC.
	(nios2_small_section_name_p): Check for regex match.
	* config/nios2/nios2.opt (mgprel-sec=): New option.
	* doc/invoke.texi (Option Summary): Add -mgprel-sec.
	(Nios II Options): Document -mgprel-sec.

	gcc/testsuite/
	* gcc.target/nios2/gpopt-gprel-sec.c: New.

From-SVN: r254123