vncserver: more debug output for xstartup

- Use "set -x" in generated xstartup.
- Announce running xstartup in logs.

builder/startup/deb/select-de.sh

@@ -198,6 +198,7 @@ generate_xstartup() {
 
   cat <<-SCRIPT > "$xstartup_script"
 #!/bin/sh
+set -x
 $de_cmd
 SCRIPT
   chmod +x "$xstartup_script"

unix/vncserver

@@ -669,9 +669,10 @@ sub RunXstartup {
   DetectAndExportDisplay();
   $ENV{VNCDESKTOP}= $desktopName;
 
+  my $xstartupCmd = "{ echo 'Running $xstartupFile'; $xstartupFile; }";
   if ($opt{'-fg'}) {
     if (! $skipxstartup) {
-      system("$xstartupFile >> " . quotedString($desktopLog) . " 2>&1");
+      system("$xstartupCmd >> " . quotedString($desktopLog) . " 2>&1");
     }
     if (IsXvncRunning()) {
       $opt{'-kill'} = ':'.$displayNumber;
@@ -680,12 +681,12 @@ sub RunXstartup {
   } else {
     if ($opt{'-autokill'}) {
       if (! $skipxstartup) {
-        system("($xstartupFile; $0 -kill :$displayNumber) >> "
+        system("($xstartupCmd; $0 -kill :$displayNumber) >> "
           . quotedString($desktopLog) . " 2>&1 &");
       }
     } else {
       if (! $skipxstartup) {
-        system("$xstartupFile >> " . quotedString($desktopLog)
+        system("$xstartupCmd >> " . quotedString($desktopLog)
           . " 2>&1 &");
       }
     }