BUILD: http: make extract_cookie_value() return an int not size_t

It's very annoying that we have to deal with the crappy size_t and with ints
at some places because these ones don't mix well. Patch 6f61b2 changed the
chunk len to int but its size remains size_t and some functions are having
trouble being used by several callers depending on the type of their arguments.

Let's turn extract_cookie_value() to int for now on, and plan a massive cleanup
later to remove all size_t.
diff --git a/include/types/buffers.h b/include/types/buffers.h
index 6280c4f..5d5ec1c 100644
--- a/include/types/buffers.h
+++ b/include/types/buffers.h
@@ -167,7 +167,7 @@
 /* describes a chunk of string */
 struct chunk {
 	char *str;	/* beginning of the string itself. Might not be 0-terminated */
-	size_t size;	/* total size of the buffer, 0 if the *str is read-only */
+	int size;	/* total size of the buffer, 0 if the *str is read-only */
 	int len;	/* current size of the string from first to last char. <0 = uninit. */
 };
 
diff --git a/src/proto_http.c b/src/proto_http.c
index 3c3bd1c..98386aa 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -8203,7 +8203,7 @@
 static char *
 extract_cookie_value(char *hdr, const char *hdr_end,
 		  char *cookie_name, size_t cookie_name_l, int list,
-		  char **value, size_t *value_l)
+		  char **value, int *value_l)
 {
 	char *equal, *att_end, *att_beg, *val_beg, *val_end;
 	char *next;
@@ -8679,7 +8679,7 @@
 find_cookie_value(struct http_msg *msg, struct http_txn *txn,
 		  const char *hdr_name, int hdr_name_len,
 		  char *cookie_name, size_t cookie_name_l, int list,
-		  char **value, size_t *value_l)
+		  char **value, int *value_l)
 {
 	struct hdr_ctx ctx;
 	int found = 0;
@@ -8706,7 +8706,7 @@
 	struct http_txn *txn = l7;
 	struct http_msg *msg = &txn->req;
 	char  *cookie_value;
-	size_t cookie_value_l;
+	int cookie_value_l;
 	int found = 0;
 
 	found = find_cookie_value(msg, txn, "Cookie", 6,
@@ -8728,7 +8728,7 @@
 	struct http_txn *txn = l7;
 	struct http_msg *msg = &txn->rsp;
 	char  *cookie_value;
-	size_t cookie_value_l;
+	int cookie_value_l;
 	int found = 0;
 
 	found = find_cookie_value(msg, txn, "Set-Cookie", 10,