CLEANUP: flt-comp: remove a no-op http_remove_header() call

CLEANUP: flt-comp: remove a no-op http_remove_header() call

In select_compression_request_header(), the "compression offload" block starts
with:

	http_remove_header(htx, &ctx);
	ctx.blk = NULL;
	while (http_find_header(htx, ist("Accept-Encoding"), &ctx, 1))
		http_remove_header(htx, &ctx);

The first call can never do anything: st->comp_algo is only set from the
"Accept-Encoding" loop above, whose exit condition is http_find_header()
returning 0, which resets ctx.blk to NULL, and http_remove_header() returns
immediately for a NULL ctx.blk. The loop that follows removes all the
occurrences of the header anyway, so the call is dead code, and it would remove
the wrong header if ctx were ever to carry another context.

Let's drop it. No functional change.