mtest: print "live" test output when verbose with only 1 test

Since running only one test sort of implies --num-processes=1 the "live"
output of the test should be printed out when --verbose option has been
given and running only a single test.

mesonbuild/mtest.py

@@ -1681,6 +1681,8 @@ class TestHarness:
             sys.exit(125)
 
         self.name_max_len = max(uniwidth(self.get_pretty_suite(test)) for test in tests)
+        self.options.num_processes = min(self.options.num_processes,
+                                         len(tests) * self.options.repeat)
         startdir = os.getcwd()
         try:
             os.chdir(self.options.wd)