put forceDelete() function to common build scripts, use it in IDEA build script

build/scripts/dist.gant

@@ -35,7 +35,7 @@ target(compile: "Compile project") {
   loadProject()
 
   project.stage("Cleaning up sandbox folder")
-  ant.delete(dir: paths.sandbox)
+  forceDelete(paths.sandbox)
 
   [paths.sandbox, paths.distWin, paths.distAll, paths.distUnix, paths.distMac, paths.artifacts, paths.artifacts_core].each {
     ant.mkdir(dir: it)

build/scripts/utils.gant

@@ -195,6 +195,29 @@ binding.setVariable("layoutMacApp", { String path, String ch, Map args ->
 
 })
 
+binding.setVariable("forceDelete", { String dirPath ->
+  // if wasn't deleted - retry several times
+  attempt = 1
+  while (attempt < 21 && (new File(dirPath).exists())) {
+    if (attempt > 1) {
+      ant.echo "Deleting $dirPath ... (attempt=$attempt)"
+
+      // let's wait a bit and try again - may be help
+      // in some cases on our windows 7 agents
+      sleep(2000)
+    }
+
+    ant.delete(failonerror: false, dir: dirPath)
+
+    attempt++
+  }
+
+  if (new File(dirPath).exists()) {
+    ant.project.log ("Cannot delete directory: $dirPath" )
+    System.exit (1)
+  }
+})
+
 binding.setVariable("patchPropertiesFile", { String where ->
   ant.echo(file: "$where/bin/idea.properties", append: "true", message:
            isEap() ?