Do not rely on GNU specific `--version-sort` option of sort

Such option is not supported by the version of sort in OSX.

Snippet used:
```
$ find src/nv-plugins/ -type f -exec sed -i "" -e "s/sort --version-sort/sort/g" {} \;
```
Merge pull request #9 from lucafavatella/do-not-rely-on-sort-version-sort-option

Do not rely on GNU specific `--version-sort` option of sort