Fix DevFS on Android devices

runtime/bin/directory.cc

Index: runtime/bin/directory.cc
diff --git a/runtime/bin/directory.cc b/runtime/bin/directory.cc
index a9b2331e5bd0bec12017e40836e426cd0ada1cc5..ccf5918f352c8dedf271e30446cd74e45213809a 100644
--- a/runtime/bin/directory.cc
+++ b/runtime/bin/directory.cc
@@ -14,6 +14,8 @@
 namespace dart {
 namespace bin {
 
+char* Directory::system_temp_path_override_ = NULL;
+
 void FUNCTION_NAME(Directory_Current)(Dart_NativeArguments args) {
   const char* current = Directory::Current();
   if (current != NULL) {
@@ -187,6 +189,17 @@ void FUNCTION_NAME(Directory_SetAsyncDirectoryListerPointer)(
 }
 
 
+void Directory::SetSystemTemp(const char* path) {
+  if (system_temp_path_override_ != NULL) {
+    free(system_temp_path_override_);
+    system_temp_path_override_ = NULL;
+  }
+  if (path != NULL) {
+    system_temp_path_override_ = strdup(path);
+  }
+}
+
+
 CObject* Directory::CreateRequest(const CObjectArray& request) {
   if ((request.Length() == 1) && request[0]->IsString()) {
     CObjectString path(request[0]);