MINOR: buffer: switch buffer sizes and offsets to size_t

Passing unsigned ints everywhere is painful, and will cause some headache
later when we'll want to integrate better with struct ist which already
uses size_t. Let's switch buffers to use size_t instead.
diff --git a/src/buffer.c b/src/buffer.c
index 79cc133..b6ece4b 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -211,9 +211,9 @@
 void buffer_dump(FILE *o, struct buffer *b, int from, int to)
 {
 	fprintf(o, "Dumping buffer %p\n", b);
-	fprintf(o, "            data=%p o=%d i=%d p=%p\n"
+	fprintf(o, "            data=%p o=%u i=%u p=%p\n"
                    "            relative:   p=0x%04x\n",
-		b->data, b->o, b->i, b->p, (unsigned int)(b->p - b->data));
+		b->data, (unsigned int)b->o, (unsigned int)b->i, b->p, (unsigned int)(b->p - b->data));
 
 	fprintf(o, "Dumping contents from byte %d to byte %d\n", from, to);
 	fprintf(o, "         0  1  2  3  4  5  6  7    8  9  a  b  c  d  e  f\n");
diff --git a/src/checks.c b/src/checks.c
index 3cae94d..0150bbb 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -2854,8 +2854,8 @@
 			}
 
 			if (check->current_step->string_len >= check->bo->size) {
-				chunk_printf(&trash, "tcp-check send : string too large (%d) for buffer size (%d) at step %d",
-					     check->current_step->string_len, check->bo->size,
+				chunk_printf(&trash, "tcp-check send : string too large (%d) for buffer size (%u) at step %d",
+					     check->current_step->string_len, (unsigned int)check->bo->size,
 					     tcpcheck_get_step_id(check));
 				set_server_check_status(check, HCHK_STATUS_L7RSP, trash.str);
 				goto out_end_tcpcheck;
diff --git a/src/flt_http_comp.c b/src/flt_http_comp.c
index b93ff69..99a767c 100644
--- a/src/flt_http_comp.c
+++ b/src/flt_http_comp.c
@@ -298,8 +298,8 @@
 	if (msg->flags & HTTP_MSGF_TE_CHNK) {
 		ret = http_compression_buffer_add_data(st, tmpbuf, zbuf, tmpbuf->i);
 		if (ret != tmpbuf->i) {
-			ha_warning("HTTP compression failed: Must consume %d bytes but only %d bytes consumed\n",
-				   tmpbuf->i, ret);
+			ha_warning("HTTP compression failed: Must consume %u bytes but only %d bytes consumed\n",
+				   (unsigned int)tmpbuf->i, ret);
 			return -1;
 		}
 	}
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 5fc7547..1eba104 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -3357,7 +3357,7 @@
 	}
 
  end:
-	trace("[%d] sent simple H2 DATA response (sid=%d) = %d bytes out (%d in, st=%s, ep=%u, es=%s, h2cws=%d h2sws=%d) buf->o=%d", h2c->st0, h2s->id, size+9, total, h1_msg_state_str(h1m->state), h1m->err_pos, h1_msg_state_str(h1m->err_state), h2c->mws, h2s->mws, buf->o);
+	trace("[%d] sent simple H2 DATA response (sid=%d) = %d bytes out (%d in, st=%s, ep=%u, es=%s, h2cws=%d h2sws=%d) buf->o=%u", h2c->st0, h2s->id, size+9, total, h1_msg_state_str(h1m->state), h1m->err_pos, h1_msg_state_str(h1m->err_state), h2c->mws, h2s->mws, (unsigned int)buf->o);
 	return total;
 }
 
@@ -3472,7 +3472,7 @@
 	}
 
 	chunk_appendf(msg, " st0=%d flg=0x%08x nbst=%u nbcs=%u fctl_cnt=%d send_cnt=%d tree_cnt=%d orph_cnt=%d dbuf=%u/%u mbuf=%u/%u",
-		      h2c->st0, h2c->flags, h2c->nb_streams, h2c->nb_cs, fctl_cnt, send_cnt, tree_cnt, orph_cnt, h2c->dbuf->i, h2c->dbuf->size, h2c->mbuf->o, h2c->mbuf->size);
+		      h2c->st0, h2c->flags, h2c->nb_streams, h2c->nb_cs, fctl_cnt, send_cnt, tree_cnt, orph_cnt, (unsigned int)h2c->dbuf->i, (unsigned int)h2c->dbuf->size, (unsigned int)h2c->mbuf->o, (unsigned int)h2c->mbuf->size);
 }
 
 /*******************************************************/
diff --git a/src/stream.c b/src/stream.c
index 9fdf662..30bfc67 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -2974,15 +2974,15 @@
 
 		chunk_appendf(&trash,
 			     " wex=%s\n"
-			     "      buf=%p data=%p o=%d p=%d req.next=%d i=%d size=%d\n",
+			     "      buf=%p data=%p o=%u p=%d req.next=%d i=%u size=%u\n",
 			     strm->req.wex ?
 			     human_time(TICKS_TO_MS(strm->req.wex - now_ms),
 					TICKS_TO_MS(1000)) : "<NEVER>",
 			     strm->req.buf,
-			     strm->req.buf->data, strm->req.buf->o,
+			     strm->req.buf->data, (unsigned int)strm->req.buf->o,
 			     (int)(strm->req.buf->p - strm->req.buf->data),
-			     strm->txn ? strm->txn->req.next : 0, strm->req.buf->i,
-			     strm->req.buf->size);
+			     strm->txn ? strm->txn->req.next : 0, (unsigned int)strm->req.buf->i,
+			     (unsigned int)strm->req.buf->size);
 
 		chunk_appendf(&trash,
 			     "  res=%p (f=0x%06x an=0x%x pipe=%d tofwd=%d total=%lld)\n"
@@ -3003,15 +3003,15 @@
 
 		chunk_appendf(&trash,
 			     " wex=%s\n"
-			     "      buf=%p data=%p o=%d p=%d rsp.next=%d i=%d size=%d\n",
+			     "      buf=%p data=%p o=%u p=%d rsp.next=%d i=%u size=%u\n",
 			     strm->res.wex ?
 			     human_time(TICKS_TO_MS(strm->res.wex - now_ms),
 					TICKS_TO_MS(1000)) : "<NEVER>",
 			     strm->res.buf,
-			     strm->res.buf->data, strm->res.buf->o,
+			     strm->res.buf->data, (unsigned int)strm->res.buf->o,
 			     (int)(strm->res.buf->p - strm->res.buf->data),
-			     strm->txn ? strm->txn->rsp.next : 0, strm->res.buf->i,
-			     strm->res.buf->size);
+			     strm->txn ? strm->txn->rsp.next : 0, (unsigned int)strm->res.buf->i,
+			     (unsigned int)strm->res.buf->size);
 
 		if (ci_putchk(si_ic(si), &trash) == -1) {
 			si_applet_cant_put(si);
@@ -3158,9 +3158,9 @@
 				     curr_strm->task->calls);
 
 			chunk_appendf(&trash,
-				     " rq[f=%06xh,i=%d,an=%02xh,rx=%s",
+				     " rq[f=%06xh,i=%u,an=%02xh,rx=%s",
 				     curr_strm->req.flags,
-				     curr_strm->req.buf->i,
+				     (unsigned int)curr_strm->req.buf->i,
 				     curr_strm->req.analysers,
 				     curr_strm->req.rex ?
 				     human_time(TICKS_TO_MS(curr_strm->req.rex - now_ms),
@@ -3179,9 +3179,9 @@
 						TICKS_TO_MS(1000)) : "");
 
 			chunk_appendf(&trash,
-				     " rp[f=%06xh,i=%d,an=%02xh,rx=%s",
+				     " rp[f=%06xh,i=%u,an=%02xh,rx=%s",
 				     curr_strm->res.flags,
-				     curr_strm->res.buf->i,
+				     (unsigned int)curr_strm->res.buf->i,
 				     curr_strm->res.analysers,
 				     curr_strm->res.rex ?
 				     human_time(TICKS_TO_MS(curr_strm->res.rex - now_ms),