First chunk of MachineInstr bundle support.

1. Added opcode BUNDLE
2. Taught MachineInstr class to deal with bundled MIs
3. Changed MachineBasicBlock iterator to skip over bundled MIs; added an iterator to walk all the MIs
4. Taught MachineBasicBlock methods about bundled MIs


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145975 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCInstrDesc.h

@@ -184,6 +184,10 @@ public:
     return NumDefs;
   }
 
+  /// getFlags - Return flags of this instruction.
+  ///
+  unsigned short getFlags() const { return Flags; }
+
   /// isVariadic - Return true if this instruction can have a variable number of
   /// operands.  In this case, the variable operands will be after the normal
   /// operands but before the implicit definitions and uses (if any are