avoid abnormal exit for FCGI worker failures

If an FCGI worker fails, which can happen for example if its TCP
connection to the FCGI server fails, we log an error message and
exit. Change the exit to always be normal to avoid filling logs with
additional process crash messages for any abnormal exits.

src/yaws_cgi.erl

@@ -772,7 +772,8 @@ fcgi_worker_fail(WorkerState, Reason) ->
     ParentPid = WorkerState#fcgi_worker_state.parent_pid,
     ParentPid ! {self(), failure, Reason},
     error_logger:error_msg("FastCGI failure: ~p~n", [Reason]),
-    exit(Reason).
+    %% exit normally to avoid filling log with crash messages
+    exit(normal).
 
 fcgi_worker_fail_if(true, WorkerState, Reason) ->
     fcgi_worker_fail(WorkerState, Reason);
@@ -826,19 +827,19 @@ fcgi_worker(ParentPid, Role, Arg, ServerConf, Options) ->
             TraceProtocol,
             LogAppError]),
     WorkerState = #fcgi_worker_state{
-                app_server_host = AppServerHost,
-                app_server_port = AppServerPort,
-                path_info = PathInfo,
-                env = Env,
-                keep_connection = false,        % Currently hard-coded; make
-                                                % configurable in the future?
-                trace_protocol = TraceProtocol,
-                log_app_error = LogAppError,
-                role = Role,
-                parent_pid = ParentPid,
-                yaws_worker_pid = Arg#arg.pid,
-                app_server_socket = AppServerSocket
-            },
+      app_server_host = AppServerHost,
+      app_server_port = AppServerPort,
+      path_info = PathInfo,
+      env = Env,
+      keep_connection = false,                % Currently hard-coded; make
+                                              % configurable in the future?
+      trace_protocol = TraceProtocol,
+      log_app_error = LogAppError,
+      role = Role,
+      parent_pid = ParentPid,
+      yaws_worker_pid = Arg#arg.pid,
+      app_server_socket = AppServerSocket
+     },
     fcgi_send_begin_request(WorkerState),
     fcgi_send_params(WorkerState, Env),
     fcgi_send_params(WorkerState, []),