Subzero: Make threads=2 and filetype=obj the testing defaults.

src/llvm2ice.cpp

Index: src/llvm2ice.cpp
diff --git a/src/llvm2ice.cpp b/src/llvm2ice.cpp
index af80ef9dc88fd52b3077b64fbbbc03cbca4e7e5a..8b73de8426419310a1bca78a02e3f3720b2fed18 100644
--- a/src/llvm2ice.cpp
+++ b/src/llvm2ice.cpp
@@ -211,7 +211,7 @@ static cl::opt<uint32_t> NumThreads(
     cl::desc("Number of translation threads (0 for purely sequential)"),
     // TODO(stichnot): Settle on a good default.  Consider
     // something related to std::thread::hardware_concurrency().
-    cl::init(0));
+    cl::init(2));
 
 static int GetReturnValue(int Val) {
   if (AlwaysExitSuccess)