vala tests: few adjustments and improvements * t/vala4.sh: Don't run 'libtoolize', it's not truly required. ($required): Don't require 'libtoolize'. (configure.ac): Don't invoke 'AC_PROG_LIBTOOL'. * t/vala-mix.sh ($required): Require 'cc'. Avoid some calls to 'framework_failure_', they were only useful when this test was xfailing (to ensure it wasn't failing for the wrong reasons). Ensure the stamp file is created in the source directory. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>