Prevent initialisation errors on Linux

[niknetniko]

The function 'getPlatform' is used before its definition. At that point, the global variable 'linuxes' is not yet initialised, resulting in errors like:

By moving all exports to the bottom, this problem should be fixed.

This is the cause of https://github.com/redhat-developer/vscode-yaml/issues/929.

[fbricon]

Thanks @niknetniko! sorry for the late merge, I missed this one during my PTO