CLEANUP: http: rename http_process_request_body()

This function does not process anything, it just waits for the beginning
of the request body. Let's rename it http_wait_for_request_body().
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index c836eb4..1b6284b 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -70,7 +70,7 @@
 int http_process_req_common(struct session *s, struct channel *req, int an_bit, struct proxy *px);
 int http_process_request(struct session *t, struct channel *req, int an_bit);
 int http_process_tarpit(struct session *s, struct channel *req, int an_bit);
-int http_process_request_body(struct session *s, struct channel *req, int an_bit);
+int http_wait_for_request_body(struct session *s, struct channel *req, int an_bit);
 int http_send_name_header(struct http_txn *txn, struct proxy* be, const char* svr_name);
 int http_wait_for_response(struct session *s, struct channel *rep, int an_bit);
 int http_process_res_common(struct session *t, struct channel *rep, int an_bit, struct proxy *px);