Remove last cleanup from captured_main_1

Remove last cleanup from captured_main_1

An earlier patch split captured_main into two parts.  This patch
removes the last remaining cleanup from captured_main_1, and also
replaces a second hand-rolled VEC-like array with a std::vector.

2016-10-21  Tom Tromey  <tom@tromey.com>

	* main.c: Include <vector>.
	(cmdarg_s): Remove typedef.  Don't define VEC.
	(captured_main_1): Use vector, not VEC.  Remove cleanups.