Fix a bug that would cause subzero to fail when --threads=0.

src/IceCompiler.cpp

Index: src/IceCompiler.cpp
diff --git a/src/IceCompiler.cpp b/src/IceCompiler.cpp
index 2db7abcda95ef96d39521b435d9320e92fb5d0f2..76c3a38616ff7100b24f9dc39da73e0000d19cee 100644
--- a/src/IceCompiler.cpp
+++ b/src/IceCompiler.cpp
@@ -141,8 +141,13 @@ void Compiler::run(const Ice::ClFlagsExtra &ExtraFlags, GlobalContext &Ctx,
   }
 
   Ctx.waitForWorkerThreads();
-  Translator->transferErrorCode();
-  Translator->emitConstants();
+  if (Translator->getErrorStatus()) {
+    Ctx.getErrorStatus()->assign(Translator->getErrorStatus().value());
+  } else {
+    Ctx.lowerGlobals("last");
+    Ctx.lowerProfileData();
+    Ctx.lowerConstants();
+  }
 
   if (Ctx.getFlags().getOutFileType() == FT_Elf) {
     TimerMarker T1(Ice::TimerStack::TT_emit, &Ctx);