Drop redundant defines

Based on TortoiseSVN revision 24916

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Fixed issue #1963: TortoiseGitMerge: Missing color config when an added line is changed

Based on TortoiseSVN revision 24917

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>