test: catch unrecognized keysyms in the xkeyboard-config test

Prompted by
https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/merge_requests/127

We run the keymap tool with --verbose which will print the messages from the
compiler to the log file as well. And then we can search for the warning
regarding an unrecognized keysym and fail our test based on that.

test/xkeyboard-config-test.py.in

@@ -42,6 +42,7 @@ def xkbcommontool(rmlvo):
         o = rmlvo.get('o', None)
         args = [
             'xkbcli-compile-keymap',  # this is run in the builddir
+            '--verbose',
             '--rules', r,
             '--model', m,
             '--layout', l,
@@ -61,6 +62,12 @@ def xkbcommontool(rmlvo):
                                              universal_newlines=True)
             if verbose:
                 print(output, file=out)
+
+            if "unrecognized keysym" in output:
+                for line in output.split('\n'):
+                    if "unrecognized keysym" in line:
+                        print('ERROR: {}'.format(line))
+                success = False
         except subprocess.CalledProcessError as err:
             print('ERROR: Failed to compile: {}'.format(' '.join(args)), file=out)
             print(err.output, file=out)