Fixed 0-cmp optimization in tarmaddnode.second_cmp64bit

Commit r28315 prevented "= 0" compare-optimizations. Should be fixed now.

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28317 3ad0048d-3df7-0310-abae-a5850022a9f2
a proposed fix to the qword_to_float64 problem

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28318 3ad0048d-3df7-0310-abae-a5850022a9f2