c-family: Fix various comment typos in c-warn.c

c-family: Fix various comment typos in c-warn.c

When looking into PR99420, I have noticed several comment typos.

2021-04-08  Jakub Jelinek  <jakub@redhat.com>

	* c-warn.c (do_warn_double_promotion): Fix comment typo,
	occured -> occurred.
	(check_alignment_of_packed_member): Fix a comment typo,
	memeber -> member.
	(warn_parm_ptrarray_mismatch): Fix comment typos, os -> of
	and onless -> unless.
	(warn_parm_array_mismatch): Fix comment typos, declaratation
	-> declaration and woud -> would.  Fix up comment indentation.