Move some flag-like props from GlobalContext and TargetLowering to ClFlags.

src/IceTypes.h

Index: src/IceTypes.h
diff --git a/src/IceTypes.h b/src/IceTypes.h
index 2cf5e401fd9f3c8597c65a04b5c3b27cd822ad6c..297fad3da6da86414362249ff969b97b5b50c905 100644
--- a/src/IceTypes.h
+++ b/src/IceTypes.h
@@ -40,6 +40,16 @@ inline Ostream &operator<<(Ostream &Stream, TargetArch Arch) {
   return Stream << targetArchString(Arch);
 }
 
+// The list of all target instruction sets. Individual targets will
+// map this to include only what is valid for the target.
+enum TargetInstructionSet {
+  X86InstructionSet_Begin,
+  // SSE2 is the PNaCl baseline instruction set.
+  X86InstructionSet_SSE2 = X86InstructionSet_Begin,
+  X86InstructionSet_SSE4_1,
+  X86InstructionSet_End,
+};
+
 enum OptLevel { Opt_m1, Opt_0, Opt_1, Opt_2 };
 
 size_t typeWidthInBytes(Type Ty);