Add support for ARMv8-M's Secure Extensions flag and intrinsics

Add support for ARMv8-M's Secure Extensions flag and intrinsics

    gcc/ChangeLog:
    2016-12-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
	        Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config.gcc (extra_headers): Added arm_cmse.h.
	* config/arm/arm-arches.def (ARM_ARCH):
	(armv8-m): Add FL2_CMSE.
	(armv8-m.main): Likewise.
	(armv8-m.main+dsp): Likewise.
	* config/arm/arm-c.c
	(arm_cpu_builtins): Added __ARM_FEATURE_CMSE macro.
	* config/arm/arm-flags.h: Define FL2_CMSE.
	* config/arm.c (arm_arch_cmse): New.
	(arm_option_override): New error for unsupported cmse target.
	* config/arm/arm.h (arm_arch_cmse): New.
	* config/arm/arm.opt (mcmse): New.
	* config/arm/arm_cmse.h: New file.
	* doc/invoke.texi (ARM Options): Add -mcmse.
	* doc/sourcebuild.texi (arm_cmse_ok): Add new effective target.
	* doc/extend.texi: Add ARMv8-M Security Extensions entry.

    gcc/testsuite/ChangeLog:
    2016-12-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
	        Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* gcc.target/arm/cmse/cmse.exp: New.
	* gcc.target/arm/cmse/cmse-1.c: New.
	* gcc.target/arm/cmse/cmse-12.c: New.
	* lib/target-supports.exp
	(check_effective_target_arm_cmse_ok): New.

    libgcc/ChangeLog:
    2016-12-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
	    Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/arm/t-arm (HAVE_CMSE): New.
	* config/arm/cmse.c: New.

Co-Authored-By: Thomas Preud'homme <thomas.preudhomme@arm.com>
From-SVN: r243187