waf: update to 2.0.8.

NEW IN WAF 2.0.8
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* Improve Windows console encoding outputs on Python 3.6 and Japanese code page #2163
* Improve msvc detection on Python 3.6 and Japanese code page #2155
* Improve moc/rcc flag parsing with msvc #2169
* Improve Eclipse project generation #2166 #2165 #2164 #2149 #2145
* Improve Boost project detection on dpkg-based systems #2146

(wiz)