One problem while compiling the ANGLE module in the Qt's source code dir

[JohnYork]

Hi, everyone !
There is a copy of ANGLE module's source code in Qt's source package, But it can not be compiled in the Qt's compiling process for the following reasons:
In the 'configure' script file, there is a compiling test on '-opengl es2' option, in the test project file 'opengles2.pro' located at '<Qt-src>/qtbase/config.tests/unix/opengles2/' requires the compiled library of ANGLE from the variable 'QMAKE_LIBS_OPENGL_ES2'. If the library files is not available, the test project will surely failed. But at this time the ANGLE module hasn't been compiled , therefore the library files are not available yet. So the test project makes the '-opengl es2' option failed, and Qt can not be compiled to support OpenGL ES2 with the ANGLE in Qt's source package, except the user can provide another compiled one.
I tried to modify the test project file 'opengles2.pro', and expected to add the ANGLE's project file to it as a sub-project. I did it like this to ignore the changing on file name and dir-structure. But the file '.qmake.cache' was required while compiling, and I don't know how to generate it.