pta: Fix comment of intra_create_variable_infos

pta: Fix comment of intra_create_variable_infos

The comment says that this function creates varinfos for *all*
variables in a function.  Meanwhile, it only creates varinfos for
parameters, the return value and the static chain.

Commiting as obvious.

gcc/ChangeLog:

	* gimple-ssa-pta-constraints.cc (make_param_constraints): Adjust
	comment: The function only creates varinfos for the parameters,
	the return value and the static chain.

Signed-off-by: Filip Kastl <fkastl@suse.cz>