Make FastAGI HANGUP show up in AGI debug output.

* Change from using send() to ast_agi_send() so the HANGUP shows up in the
AGI debug output.

(closes issue ASTERISK-18723)
Reported by: James Van Vleet
Patches:
      jira_asterisk_18723_v1.8.patch (license #5621) patch uploaded by rmudgett


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@345431 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_agi.c

@@ -3483,7 +3483,7 @@ static enum agi_result run_agi(struct ast_channel *chan, char *request, AGI *agi
 				if (pid > -1) {
 					kill(pid, SIGHUP);
 				} else if (agi->fast) {
-					send(agi->ctrl, "HANGUP\n", 7, 0);
+					ast_agi_send(agi->fd, chan, "HANGUP\n");
 				}
 			}
 		}
@@ -3598,7 +3598,7 @@ static enum agi_result run_agi(struct ast_channel *chan, char *request, AGI *agi
 			}
 			waitpid(pid, status, WNOHANG);
 		} else if (agi->fast) {
-			send(agi->ctrl, "HANGUP\n", 7, 0);
+			ast_agi_send(agi->fd, chan, "HANGUP\n");
 		}
 	}
 	fclose(readf);