[LLVMdev] Cleanup of constant sequence type construction

[Daniel Dunbar]

The methods for constructing constant sequencish types (struct, array, vector) aren't 
consistent and we are missing a few useful convenience methods. I would like to change
the interfaces to each support four construction methods: 
 (a) With and without a type.
 (b) With a vector or an array + size.

Here:
--
ConstantStruct {
  static Constant *get(const StructType *T, 
                       Constant*const* Vals, unsigned NumVals, 
                       bool Packed = false);
  static Constant *get(const StructType *T, const std::vector<Constant*> &V);
  static Constant *get(Constant*const* Vals, unsigned NumVals,
                       bool Packed = false);
  static Constant *get(const std::vector<Constant*> &V, bool Packed = false);
}

ConstantAray {
  static Constant *get(const ArrayType *T,
                       Constant*const* Vals, unsigned NumVals);
  static Constant *get(const ArrayType *T, const std::vector<Constant*> &);
  static Constant *get(Constant*const* Vals, unsigned NumVals);
  static Constant *get(const std::vector<Constant*> &);
}

ConstantVector {
  static Constant *get(const VectorType *T,
                       Constant*const* Vals, unsigned NumVals);
  static Constant *get(const VectorType *T, const std::vector<Constant*> &);
  static Constant *get(Constant*const* Vals, unsigned NumVals);
  static Constant *get(const std::vector<Constant*> &V);
}
--

While I am at it it would make sense to make the array + size methods more
efficient (not construct a vector).

Any problems?

 - Daniel