--launcher-show-set-environment-commands uses wrong separator

[jcfr]

When using the option --launcher-show-set-environment-commands on windows within Git bash, the list of path are separated using ; whereas : is expected.

For example, in a posix shell on either windows or unix, the following is expected:

PATH=/path/thing1:/path/thing2
PYTHONPATH=/path/module1:/path/module2

but on windows, in a posix shell .. the following is returned:

PATH=/path/thing1;/path/thing2
PYTHONPATH=/path/module1;/path/module2

The issue is here in function generateEnvironmentScript.

An internal function named pathSep(bool posix) could be added.

Reported by @vovythevov