warn-access: Comment spelling fixes

I've noticed various spelling bugs in comments in this file.

There is one spot I haven't fixed:
"Otherwise, VAR is the auto variable
(including an unnamed temporary such as a compound literal) whose
lifetime's rended it dangling."
I'm afraid I don't know what it wanted to say, "lifetime rendered it"
or something else?

2022-03-01  Jakub Jelinek  <jakub@redhat.com>

	* gimple-ssa-warn-access.cc (warn_string_no_nul,
	maybe_warn_nonstring_arg, fndecl_alloc_p, new_delete_mismatch_p,
	matching_alloc_calls_p, maybe_warn_alloc_args_overflow,
	pass_waccess::check_alloca, pass_waccess::check_strcat,
	memmodel_to_uhwi, fntype_argno_type,
	pass_waccess::maybe_check_access_sizes,
	pass_waccess::check_call_access,
	pass_waccess::maybe_check_dealloc_call, pass_waccess::check_stmt):
	Comment spelling fixes.