BUILD/MEDIUM: da: Necessary code changes for new buffer API.

The most significant change from 1.8 to >=1.9 is the buffer
data structure, using the new field and fixing along side
a little hidden compilation warning.

This must be backported to 1.9.
diff --git a/src/da.c b/src/da.c
index 61d6422..0a49d52 100644
--- a/src/da.c
+++ b/src/da.c
@@ -309,7 +309,7 @@
 	hidx = &smp->strm->txn->hdr_idx;
 	hmsg = &smp->strm->txn->req;
 
-	while (http_find_next_header(hmsg->chn->buf->p, hidx, &hctx) == 1 &&
+	while (http_find_next_header(ci_head(hmsg->chn), hidx, &hctx) == 1 &&
 	        nbh < DA_MAX_HEADERS) {
 		char *pval;
 		size_t vlen;
@@ -331,7 +331,7 @@
 				atlas);
 		} else if (strcmp(hbuf, "Cookie") == 0) {
 			char *p, *eval;
-			int pl;
+			size_t pl;
 
 			eval = pval + hctx.vlen;
 			/**