system.h (ASM_IDENTIFY_GCC, [...]): Poison.

	* system.h (ASM_IDENTIFY_GCC, STDC_VALUE, TRAMPOLINE_ALIGN,
	ASM_IDENTIFY_GCC_AFTER_SOURCE): Poison.
	* config/pdp11/pdp11.h (TRAMPOLINE_ALIGN): Rename to
	TRAMPOLINE_ALIGNMENT.
	* config/arm/arm.h, config/mcore/mcore.h: Likewise.  Change value
	to be in bits.
	* config/i386/cygwin.h (PCC_BITFIELDS_TYPE_MATTERS): Rename to
	PCC_BITFIELD_TYPE_MATTERS.
	* config/interix.h (STDC_VALUE): Remove.  Use
	STDC_0_IN_SYSTEM_HEADERS.
	* config/darwin.h (ASM_IDENTIFY_GCC), config/dsp16xx/dsp16xx.h
	(ASM_IDENTIFY_GCC), config/stormy16/stormy16.h (ASM_IDENTIFY_GCC,
	ASM_IDENTIFY_GCC_AFTER_SOURCE): Remove.

From-SVN: r48877