[th/va-args-join] change implementation of `NM_UTILS_{LOOKUP,ENUM2STR}_DEFINE()`
this is to avoid a lgtm.com warning:
https://lgtm.com/projects/g/NetworkManager/NetworkManager/?mode=tree&ruleFocus=1506698658528
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this is to avoid a lgtm.com warning:
https://lgtm.com/projects/g/NetworkManager/NetworkManager/?mode=tree&ruleFocus=1506698658528