tests: don't always look for a C++ compiler named 'RCC' On MacOS X (10.8), since the file system is case-insensitive, RCC can point to the "Resource Compiler" of the Qt4 Toolkit: <http://doc.qt.digia.com/4.2/rcc.html> That mismatch causes our configure script to erroneously think that no working C++ compiler is present, and that is thus necessary to skip all the test cases requiring such a compiler. So only look for a compiler named 'RCC' if the file system is case-sensible. Issue spotted analyzing the testsuite logs reported in bug#13317. * configure.ac: Adjust. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>