Trace and quote with argv: get rid of unneeded count argument.

Trace and quote with argv: get rid of unneeded count argument.

Now that str_buf takes care of all the allocations, there is
no more gain to pass an argument count.

So this patch removes the "count" argument from:
	- "sq_quote_argv"
	- "trace_argv_printf"
and all the callers.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>