windows: in some cases this is required to support slashes

problem detected in file history (could be pipe related)

Quoting executable path allow to fix the problem :

C:\>"C:/GitStack/git/bin/git.exe" --git-dir="C:/GitStack/repositories/GitPHP.git" rev-list a313db247edc31f5a770383c1ea7ee89dd5cf4c0 ^
--no-merges --max-count=101 -- include/controller | "C:/GitStack/git/bin/git.exe" --git-dir="C:/GitStack/repositories/GitPHP.git" diff-tree -r --stdin -- include/controller

Note: the ^ is a line separator on windows (like \ on linux)