[PATCH] guiddef.h: Improve __uuidof implementation.

[Jacek Caban]

This patch ensures that the reference is unique and identical for all 
uses in module, fixes handling of const types and uses direct reference 
instead of depending on optimizer to produce sane code.

Based on patch by Kevin Puetz.

Signed-off-by: Jacek Caban <jacek(a)codeweavers.com>
---
  include/guiddef.h | 39 +++++++++++++++++++++++++++------------
  1 file changed, 27 insertions(+), 12 deletions(-)