[3.12] gh-111165: Add missed "support." prefix for "verbose" (GH-111327…

…) (GH-111328)

(cherry picked from commit a498192)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/test/libregrtest/single.py

@@ -70,7 +70,7 @@ def _run_suite(suite):
             err = result.failures[0][1]
         else:
             err = "multiple errors occurred"
-            if not verbose: err += "; run in verbose mode for details"
+            if not support.verbose: err += "; run in verbose mode for details"
         errors = [(str(tc), exc_str) for tc, exc_str in result.errors]
         failures = [(str(tc), exc_str) for tc, exc_str in result.failures]
         raise support.TestFailedWithDetails(err, errors, failures, stats=stats)