* fold-const.c (fold_truthop): Use can_use_bit_fields_p.
	(fold): Likewise.
	* langhooks.c (lhd_can_use_bit_fields_p): New function.
	* langhooks-def.h (lhd_can_use_bit_fields_p): Declare.
	(LANG_HOOKS_CAN_USE_BIT_FIELDS_P): New define.
	(LANG_HOOKS_INITIALIZER): Use it.
	* langhooks.h (struct lang_hooks) [can_use_bit_fields_p]: New
	field.

From-SVN: r56498