Fixed issue #2362: git.exe get stuck on Win XP

Make sure STARTUPINFO structures are initialized

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Use our own infrastructure for version checks

Signed-off-by: Sven Strickroth <email@cs-ware.de>