[arm] Use arm_active_target when configuring builtins

[arm] Use arm_active_target when configuring builtins

This patch uses the new ISA data structure to determine which builtins
to add.  It entirely eliminates the need for insn_flags to be a global
variable, but we're about to delete that in the following patches, so
for now we leave it as a global.

	* arm-builtins.c: Include sbitmap.h.
	(def_mbuiltin): Change first parameter to a flag bit.  Use it to test
	available features in the current target.
	(struct builtin_description): Change type of feature field.
	(IWMMXT_BUILTIN): Use the isa_features types.
	(IWMMXT2_BUILTIN): Likewise.
	(IWMMXT_BUILTIN2): Likewise.
	(IWMMXT2_BUILTIN2): Likewise.
	(CRC32_BUILTIN): Likewise.
	(CRYPTO_BUILTIN): Likewise.
	(iwmmx_builtin): Likewise.
	(iwmmx2_builtin): Likewise.
	(arm_iwmmxt_builtin): Check for specific feature bits.

From-SVN: r243702