CTF: set up debug info for function arguments

CTF: set up debug info for function arguments

Added this support in read_func_kind_type after gcc started generating
CTF for function arguments.

Replaced XNEW with std::vector and NULL with nullptr.

Expanded gdb.base/ctf-ptype.exp to test function arguments. Also fixed
some typos.

gdb/ChangeLog:

	* ctfread.c (read_func_kind_type): Set up function arguments.

gdb/testsuite/ChangeLog:

	* gdb.base/ctf-ptype.exp: Add function tests and fix typos.