Add -march=icelake.

Add -march=icelake.

gcc/
	* config.gcc: Add -march=icelake.
	* config/i386/driver-i386.c (host_detect_local_cpu): Detect icelake.
	* config/i386/i386-c.c (ix86_target_macros_internal): Handle icelake.
	* config/i386/i386.c (processor_costs): Add m_ICELAKE.
	(PTA_ICELAKE, PTA_AVX512VNNI, PTA_GFNI, PTA_VAES, PTA_AVX512VBMI2,
	PTA_VPCLMULQDQ, PTA_RDPID, PTA_AVX512BITALG): New.
	(processor_target_table): Add icelake.
	(ix86_option_override_internal): Handle new PTAs.
	(get_builtin_code_for_version): Handle icelake.
	(M_INTEL_COREI7_ICELAKE): New.
	(fold_builtin_cpu): Handle icelake.
	* config/i386/i386.h (TARGET_ICELAKE, PROCESSOR_ICELAKE): New.
	* doc/invoke.texi: Add -march=icelake.
gcc/testsuite/
	* gcc.target/i386/funcspec-56.inc: Handle new march.
	* g++.dg/ext/mv16.C: Ditto.
libgcc/
	* config/i386/cpuinfo.h (processor_subtypes): Add INTEL_COREI7_ICELAKE.

From-SVN: r257331