* i386: improvements to 64-bit comparison code, also serves as a good base for m68k target:
  * Better handling of LOC_CREGISTER locations.
  + Support direct compares of constants with references.
  + Optimize away comparison of low dword when its result is constant (cases of "less" and "greater or equal" comparing against a constant with zero low dword).


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28263 3ad0048d-3df7-0310-abae-a5850022a9f2