Do not allow VERSION to be overloaded by build system.
Do not allow VERSION to be overloaded by build system.

When integrating finit as a component in another system, that build
system may set VERSION as an environment variable for that OS -- we do
not want that version to be set as the version of finit.

Also, bump version to 2.0.1-dev for upcoming patch release cycle.

Signed-off-by: Joachim Nilsson <583c295fd7602c168ad814279bbc3894ba65f5d6@gmail.com>

troglobit/finit,troglobit/finit,westermo/finit,westermo/finit