Revert r325224 "Report fatal error in the case of out of memory"

It caused fails on some buildbots.

llvm-svn: 325227
diff --git a/llvm/lib/CodeGen/LiveIntervalUnion.cpp b/llvm/lib/CodeGen/LiveIntervalUnion.cpp
index 84b3294..3e742a6 100644
--- a/llvm/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalUnion.cpp
@@ -187,7 +187,7 @@
   clear();
   Size = NSize;
   LIUs = static_cast<LiveIntervalUnion*>(
-      llvm::malloc(sizeof(LiveIntervalUnion)*NSize));
+    malloc(sizeof(LiveIntervalUnion)*NSize));
   for (unsigned i = 0; i != Size; ++i)
     new(LIUs + i) LiveIntervalUnion(Alloc);
 }