Log Message:
Updated waf to 1.9.2.

NEW IN WAF 1.9.2
----------------
* Fix a Python 3 encoding error when displaying the file hash in 'waf dist' #1769
* Force qt5 static library detection with 'QT5_XCOMPILE=1 QT5_FORCE_STATIC=1 waf \ 
configure' #1588
* Force the parent os.environ value as default in pre-forked processes #1791
* Support flexflags as arguments #1782
* Update a few extensions: xcode, pytest, msvcdeps, cppcheck, win32_opts, codelite
* Store Task.last_cmd selectively, so that extensions can use them \ 
(clang_compilation_database)
* Set TaskBase.keep_last_cmd to keep the last command executed
* New pyqt5 extension #1790
* Remove all non-BSD code from the Waf archive file

NEW IN WAF 1.9.1
----------------

* Execute proceses with run_regular_process when arguments are not serializable #1764
* Do not de-duplicate configuration flags assigned through uselib_store \ 
(conf.check tests)
* Let the documentation scripts generate SVG outputs