use child_process member "args" instead of string array variable

use child_process member "args" instead of string array variable

Use run_command() with a struct child_process variable and populate its
"args" member directly instead of building a string array and passing it
to run_command_v_opt().  This avoids the use of magic index numbers and
makes simplifies the possible addition of more arguments in the future.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Taylor Blau <me@ttaylorr.com>