Turn parallel compilation back on.

Apparently we don't wind back class statuses any more.

Change-Id: Ice0c743114e62aa805d170aa62f317007b9dbdb4
diff --git a/src/dex2oat.cc b/src/dex2oat.cc
index 088cb45..e9acbad 100644
--- a/src/dex2oat.cc
+++ b/src/dex2oat.cc
@@ -475,7 +475,7 @@
   uintptr_t image_base = 0;
   UniquePtr<std::string> host_prefix;
   std::vector<const char*> runtime_args;
-  int thread_count = 2;
+  int thread_count = sysconf(_SC_NPROCESSORS_CONF);
   bool support_debugging = false;
 #if defined(__arm__)
   InstructionSet instruction_set = kThumb2;
@@ -563,10 +563,6 @@
     }
   }
 
-#if !defined(ART_USE_LLVM_COMPILER)
-  thread_count = 1;
-#endif
-
   if (oat_filename.empty() && oat_fd == -1) {
     Usage("Output must be supplied with either --oat-file or --oat-fd");
   }