reduce conditional compilation for LOAD_EXTEND_OP

reduce conditional compilation for LOAD_EXTEND_OP

Provide a default in files where that is possible, so that everything
else there can be unconditionally compiled.  However rtlanal.c and
reload.c do tricky things that break providing a global default, so we
can't do that yet.

gcc/ChangeLog:

2015-07-08  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* combine.c (try_combine): Don't check if LOAD_EXTEND_OP is
	defined.
	(simplify_set): Likewise.
	* cse.c (cse_insn): Likewise.
	* fold-const.c (fold_single_bit_test): Likewise.
	(fold_unary_loc): Likewise.
	* postreload.c (reload_cse_simplify_set): Likewise.
	(reload_cse_simplify_operands): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@225591 138bc75d-0d04-0410-961f-82ee72b054a4