Building Qt 5.8 from git with prop codecs: Qmake unknown feature - mirclient

[Thomas233]

Hello,

I want to build qt 5.8 with webengine proprietary codecs enabled. This is a follow-up to my problems with 5.7, which I could not yet to work on the target machine. Therefore I am going to switch directly over to 5.8 as it has gone final.

This are my commands:

git clone https://code.qt.io/qt/qt5.git  
cd qt5
git checkout 5.8
perl init-repository
./configure -prefix "/opt/Qt/5.8/gcc_64" -opensource -nomake examples -nomake tests -release
cd qtwebengine
 ../qtbase/bin/qmake WEBENGINE_CONFIG+=use_proprietary_codecs

However, this is the error I get when calling qmake:
Unknown feature: mirclient

What is mirclient (I didnt get that with 5.7 which I`ve compiled in the same way) ?

Is the order of commands correct ? What is the proper way of commands to build 5.8 from git, I am not coming behind :-/

Thank you !