uim-1.5.7 contained a compatability patch for qt-4.7 (bug #331133) but was purged from portage. On amd64 (and x86?), current stable version of uim will fail to emerge when current stable version of x11-libs/qt-core is installed, and USE=qt4 is used.
Sorry, typo: uim-1.5.7-r1 was the ebuild that contained the qt-4.7 compatibility patch.
*** This bug has been marked as a duplicate of bug 331133 ***