* lcm.c (output.h): #include.

	* lcm.c (output.h): #include.
	(compute_earliest): Remove hack to treat renumbered EXIT_BLOCK
	as an ordinary block.
	(optimize_mode_switching): Don't pretend that the exit block is
	an ordinary block, or handle sucessors of entry block specially.
	Instead, split edges from entry block and to exit block, and
	put a computing definition on the thus gained post-entry-block,
	and a need on the pre-exit-block.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@54064 138bc75d-0d04-0410-961f-82ee72b054a4