Clean up some usage of Triple.  The base class has methods for determining if the target is iOS and Linux.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189604 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/ExecutionEngine/TargetSelect.cpp b/lib/ExecutionEngine/TargetSelect.cpp
index 558d8b3..9b7d348 100644
--- a/lib/ExecutionEngine/TargetSelect.cpp
+++ b/lib/ExecutionEngine/TargetSelect.cpp
@@ -91,7 +91,7 @@
   // FIXME: non-iOS ARM FastISel is broken with MCJIT.
   if (UseMCJIT &&
       TheTriple.getArch() == Triple::arm &&
-      TheTriple.getOS() != Triple::IOS &&
+      !TheTriple.isiOS() &&
       OptLevel == CodeGenOpt::None) {
     OptLevel = CodeGenOpt::Less;
   }