The following splits "tree alias analysis"'s pieces into more
fine-grained timevars, since each individual piece of what it does can
take a very long time, and because it's really performing a bunch of
separate passes.

Bootstrapped and regtested on i686-darwin
Committed to mainline

2007-07-28  Daniel Berlin  <dberlin@dberlin.org>

	* timevar.def: Add TV_CALL_CLOBBER, TV_FLOW_SENSITIVE,
	TV_FLOW_INSENSITIVE.

	* tree-ssa-alias.c (compute_call_clobbered): Push/pop
	TV_CALL_CLOBBER.
	(compute_flow_sensitive_aliasing): Ditto for TV_FLOW_SENSITIVE.
	(compute_flow_insensitive_aliasing): Ditto for
	TV_FLOW_INSENSITIVE.