Only MGT_Complain() on stderr when -d or -F flags given.

bin/varnishd/mgt/mgt.h

@@ -176,6 +176,7 @@ extern const char C_INFO[];	// Normal stuff, keep a record for later
 extern const char C_DEBUG[];	// More detail than you'd normally want
 extern const char C_SECURITY[];	// Security issues
 extern const char C_CLI[];	// CLI traffic between master and child
+extern int complain_to_stderr;
 
 /* mgt_param.c */
 void MCF_InitParams(struct cli *);

bin/varnishd/mgt/mgt_main.c

@@ -579,6 +579,9 @@ main(int argc, char * const *argv)
 	if (!d_flag && b_arg == NULL && !f_flag)
 		ARGV_ERR("Neither -b nor -f given. (use -f '' to override)\n");
 
+	if (d_flag || F_flag)
+		complain_to_stderr = 1;
+
 	/*
 	 * Start out by closing all unwanted file descriptors we might
 	 * have inherited from sloppy process control daemons.

bin/varnishd/mgt/mgt_util.c

@@ -49,6 +49,8 @@
 #include "vav.h"
 #include "vct.h"
 
+int complain_to_stderr;
+
 /*--------------------------------------------------------------------*/
 
 char *
@@ -170,7 +172,7 @@ MGT_Complain(const char *loud, const char *fmt, ...)
 	else
 		WRONG("Wrong complaint loudness");
 
-	if (loud != C_CLI)
+	if (complain_to_stderr && loud != C_CLI)
 		fprintf(stderr, "%s %s\n", loud, VSB_data(vsb));
 
 	if (!MGT_DO_DEBUG(DBG_VTC_MODE))