MPS: Change some macros to functions

[Gerd Möllmann]

Any objections against changing these to functions?

  #define IGC_HEADER_NWORDS(h) ((h)->v >> IGC_HEADER_NWORDS_SHIFT)
  #define IGC_HEADER_HASH(h) (((h)->v >> IGC_HEADER_HASH_SHIFT) & 
IGC_HEADER_HASH_MASK)
  #define IGC_HEADER_TYPE(h) (((h)->v >> IGC_HEADER_TYPE_SHIFT) & 
IGC_HEADER_TYPE_MASK)
  #define IGC_HEADER_TAG(h) ((h)->v & IGC_HEADER_TAG_MASK)

LLDB can't handle macros, and having return types would also be nice.

I can do that if you agree.