Due to some extraneous quotation marks in config.tests/unix/fvisibility.test, the symbol visibility test fails. The problem is that $COMPILER includes the --sysroot argument, and so is not the name of an executable. meta/recipes-qt/qt4/files/fix-config-test.patch is a now-abandoned (should be deleted?) patch that fixes this issue in qt-4.5, and an issue in another test that is now fixed upstream.
Unfortunately I think we have to say we're not going to get to this - qt4 is unsupported upstream and we're not very actively maintaining the meta-qt4 layer. (If someone were to send a patch we'd likely integrate it, however.)