ctfc: get rid of the static variable in ctf_list_add_ctf_vars ()

2022-04-14  Indu Bhagat  <indu.bhagat@oracle.com>

gcc/ChangeLog:

	* ctfc.h (struct ctf_container): Introduce a new member.
	* ctfout.cc (ctf_list_add_ctf_vars): Use it instead of static
	variable.