[autotest] tst_qglyphrun tends to fail on OSX 10.8

This test tends to fail on macx-clang_developer-build_OSX_10.8 stage.
2013-07-28 00:29:24.664 tst_qglyphrun[28566:707] Unable to register font: Error Domain=com.apple.coretext Code=-1 "The operation couldn’t be completed. (com.apple.coretext error -1 - Could not register the font file 'file://localhost/work/build/qtbase/tests/auto/gui/text/qglyphrun/test.ttf')" UserInfo=0x100e48f70

{NSDescription=Could not register the font file 'file://localhost/work/build/qtbase/tests/auto/gui/text/qglyphrun/test.ttf', CTFailedFontFileURL=file://localhost/work/build/qtbase/tests/auto/gui/text/qglyphrun/test.ttf}

FAIL! : tst_QGlyphRun::drawMultiScriptText2() Compared values are not the same
Loc: [tst_qglyphrun.cpp(505)]

See for example http://testresults.qt-project.org/ci/Qt5_release_Integration/build_00200/macx-clang_developer-build_OSX_10.8/log.txt.gz