* tree-phinodes.c (remove_phi_node): Add argument
	RELEASE_LHS_P.  If given, release the SSA name on the LHS of
	the PHI node.
	Update all users.
	* tree-ssa-dce.c: Remove forward declarations for static
	functions.  Re-arrange functions bodies as needed.
	(find_obviously_necessary_stmts): Never mark PHI nodes as
	obviously necessary.

From-SVN: r119740