Fixed broken environment on restart.

Fixed broken environment on restart.

We were calling duplicate_environment() to copy the service's initial
environment prior to restarting it.  However the duplicate_environment()
function modified its input by replacing = characters with NULLs.  That
is not allowed; the memory returned by GetEnvironmentStrings() must be
treated as readonly.

After two restarts the application would run with a null environment and
probably crash.

We now copy the initial environment on to the heap and operate on the
copy, ensuring that the corruption does not occur.

Thanks Alessandro Gherardi.