[test] Print the log output on failure.

This ensures that if the assertion fails we dump the log content. This
should help me investigate what the output looks like on Windows, where
the test is failing.

llvm-svn: 371899

Author: JDevlieghere

lldb/packages/Python/lldbsuite/test/api/log/TestAPILog.py

@@ -44,5 +44,5 @@ def cleanup():
         create_target = 'lldb::SBTarget lldb::SBDebugger::CreateTarget(const char *) (0x{}, "")'.format(
             debugger_addr)
 
-        self.assertTrue(get_scripting_language in log)
-        self.assertTrue(create_target in log)
+        self.assertTrue(get_scripting_language in log, log)
+        self.assertTrue(create_target in log, log)