Log Message:
Updated waf to 1.9.11.

NEW IN WAF 1.9.11
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* Detect Visual Studio 2017 Build Tools using vswhere.exe #1945
* Improve preprocessor performance on system paths in verbose mode #1950
* Better installation defaults for windows import libraries #1860
* cpplint enhancements: --cpplint-root #1953 #1956
* eclipse project generator enhancements #1957 #1958