Enable Intel PCONFIG instruction.

Enable Intel PCONFIG instruction.

Intel has disclosed a set of new instructions for Icelake processor.
The spec is
https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf

This patch enables Intel PCONFIG instruction.

gas/
	* config/tc-i386.c (cpu_arch): Add .pconfig.
	* doc/c-i386.texi: Document .pconfig.
	* testsuite/gas/i386/i386.exp: Add PCONFIG tests.
	* testsuite/gas/i386/pconfig-intel.d: New test.
	* testsuite/gas/i386/pconfig.d: Likewise.
	* testsuite/gas/i386/pconfig.s: Likewise.
	* testsuite/gas/i386/x86-64-pconfig-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-pconfig.d: Likewise.
	* testsuite/gas/i386/x86-64-pconfig.s: Likewise.
opcodes/
	* i386-dis.c (enum): Add pconfig.
	* i386-gen.c (cpu_flag_init): Add CPU_PCONFIG_FLAGS.
	(cpu_flags): Add CpuPCONFIG.
	* i386-opc.h (enum): Add CpuPCONFIG.
	(i386_cpu_flags): Add cpupconfig.
	* i386-opc.tbl: Add PCONFIG instruction.
	* i386-init.h: Regenerate.
	* i386-tbl.h: Likewise.