Mac OS X doesn't have strchrnul

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>
Use kqueue as a replacement of signalfd

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>
fix -Werror,-Wtautological-constant-out-of-range-compare
check availability of versionsort()
fix -Werror,-Wenum-conversion

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>
fix -Werror,-Wunused-const-variable

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>
higher baud rate may not have been defined

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>
linux dependent bits

Signed-off-by: You-Sheng Yang (楊有勝) <vicamo@gmail.com>