Fix race condition in Directory.create.

runtime/bin/directory_android.cc

Index: runtime/bin/directory_android.cc
diff --git a/runtime/bin/directory_android.cc b/runtime/bin/directory_android.cc
index dbdfca77744f937bae8e721d07fd4745a72ff988..f3f471fd0e21594fddde6158711f2a0c8013f06f 100644
--- a/runtime/bin/directory_android.cc
+++ b/runtime/bin/directory_android.cc
@@ -391,7 +391,12 @@ char* Directory::Current() {
 bool Directory::Create(const char* dir_name) {
   // Create the directory with the permissions specified by the
   // process umask.
-  return (TEMP_FAILURE_RETRY(mkdir(dir_name, 0777)) == 0);
+  int result = TEMP_FAILURE_RETRY(mkdir(dir_name, 0777));
+  // If the directory already exists, treat it as a success.
+  if (result == -1 && errno == EEXISTS)  {
+    return (Exists(dir_name) == EXISTS);
+  }
+  return (result == 0);
 }