Win32 CONDITION_VARIABLE has better performance and is easier to
maintain.
Since CONDITION_VARIABLE is not available in Windows XP and below,
old implementation of pthread_cond_t is kept under define guard
'GIT_WIN_XP_SUPPORT'. To enable old implementation, build with
make CFLAGS="-DGIT_WIN_XP_SUPPORT".
Signed-off-by: Loo Rong Jie <loorongjie@gmail.com>
fast-forwarded.