Add march=knl.

Add march=knl.

gcc/

	* config.gcc: Support "knl".
	* config/i386/driver-i386.c (host_detect_local_cpu): Detect "knl".
	* config/i386/i386-c.c (ix86_target_macros_internal): Handle
	PROCESSOR_KNL.
	* config/i386/i386.c (m_KNL): Define.
	(processor_target_table): Add "knl".
	(PTA_KNL): Define.
	(ix86_issue_rate): Add PROCESSOR_KNL.
	(ix86_adjust_cost): Ditto.
	(ia32_multipass_dfa_lookahead): Ditto.
	(get_builtin_code_for_version): Handle "knl".
	(fold_builtin_cpu): Ditto.
	* config/i386/i386.h (TARGET_KNL): Define.
	(processor_type): Add PROCESSOR_KNL.
	* config/i386/i386.md (attr "cpu"): Add knl.
	* config/i386/x86-tune.def: Add m_KNL.

gcc/testsuite/

	* gcc.target/i386/funcspec-5.c: Test avx512f and knl.

From-SVN: r218610