msys-bash: Upgrade to 3.1.23

Signed-off-by: Thomas Braun <thomas.braun@byte-physics.de>
msys-bash: Disable parallel make

As parallel builds occasionally fail.
This also removes the need to pass "-j1" to mgwmake.

Signed-off-by: Thomas Braun <thomas.braun@byte-physics.de>
Merge pull request #26 from t-b/upgrade_bash

msys-bash: Upgrade to 3.1.23