vircapstest: Properly report error for failed tests
    
    There are two macros used in the test: CAPSCOMP and CAPS_EXPECT_ERR.
    Both run a test case and if a failure occurred, they set the @ret
    variable to a value of -1 to indicate an error. Well, that's what they
    should do. Due to a typo, they set the variable to a positive one
    effectively masking any failed test.
    
    Then, we have couple of tests failing. Fix them too.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>