MEDIUM: http: add the "set-nice" action to http-request and http-response

This new action changes the nice factor of the task processing the current
request.
diff --git a/include/types/proto_http.h b/include/types/proto_http.h
index 6190e6c..b50375f 100644
--- a/include/types/proto_http.h
+++ b/include/types/proto_http.h
@@ -246,6 +246,7 @@
 	HTTP_REQ_ACT_ADD_HDR,
 	HTTP_REQ_ACT_SET_HDR,
 	HTTP_REQ_ACT_REDIR,
+	HTTP_REQ_ACT_SET_NICE,
 	HTTP_REQ_ACT_MAX /* must always be last */
 };
 
@@ -256,6 +257,7 @@
 	HTTP_RES_ACT_DENY,
 	HTTP_RES_ACT_ADD_HDR,
 	HTTP_RES_ACT_SET_HDR,
+	HTTP_RES_ACT_SET_NICE,
 	HTTP_RES_ACT_MAX /* must always be last */
 };
 
@@ -368,6 +370,7 @@
 			struct list fmt;       /* log-format compatible expression */
 		} hdr_add;                     /* args used by "add-header" and "set-header" */
 		struct redirect_rule *redir;   /* redirect rule or "http-request redirect" */
+		int nice;                      /* nice value for HTTP_REQ_ACT_SET_NICE */
 	} arg;                                 /* arguments used by some actions */
 };
 
@@ -381,6 +384,7 @@
 			int name_len;          /* header name's length */
 			struct list fmt;       /* log-format compatible expression */
 		} hdr_add;                     /* args used by "add-header" and "set-header" */
+		int nice;                      /* nice value for HTTP_RES_ACT_SET_NICE */
 	} arg;                                 /* arguments used by some actions */
 };