FLTK examples are broken after Mesa update to 20.2

[danfe]

Looking at the previous build logs, some (obsolete?) symbols or definitions were placed in the inlcude/GL/gl[x]_mangle.h files which are no longer installed by Mesa v20.2, leading to the following errors:

.../oyranos-0.9.6/src/examples/image_display/Oy_Fl_Shader_Box.h:71:5: error: use of undeclared identifier 'glGetObjectParameterivARB'; did you mean 'glGetTexParameteriv'?
    glGetObjectParameterivARB (obj, GL_OBJECT_INFO_LOG_LENGTH_ARB, &len);
    ^~~~~~~~~~~~~~~~~~~~~~~~~
    glGetTexParameteriv
/usr/local/include/GL/gl.h:1274:23: note: 'glGetTexParameteriv' declared here
GLAPI void GLAPIENTRY glGetTexParameteriv( GLenum target,
                      ^
In file included from .../oyranos-0.9.6/src/examples/image_display/image_display.cpp:46:
.../oyranos-0.9.6/src/examples/image_display/Oy_Fl_Shader_Box.h:75:2: error: use of undeclared identifier 'glGetInfoLogARB'
        glGetInfoLogARB (obj, len, &nwritten, log);