If QHttp or QFtp add-on module is downloaded as a tar.gz package the source tree is missing the .git and the header files aren't added to the include directory

The problem appears to be that if .git directory is missing from the source tree git_build flag doesn't get added to QMAKE_PRL_CONFIG in lib/libQt5Http.prl.

If .git is missing then the header files aren't added to the include directory.

As a woraround one can create an empty .git directory in source tree to get git_build flag in place.