tests: Add another GMarkup test from oss-fuzz

This doesn’t trigger any new failures, but is distinct from other tests
we have, so would be good to retain.

Related to commit cec71705

.
Signed-off-by: Philip Withnall <withnall@endlessm.com>

glib/tests/Makefile.am

@@ -184,7 +184,7 @@ markup_tests = \
 	fail-36 fail-37 fail-38 fail-39 fail-40 \
 	fail-41 fail-42 fail-43 fail-44 fail-45 \
 	fail-46 fail-47 fail-48 fail-49 fail-50 \
-	fail-51 \
+	fail-51 fail-52 fail-53 \
 	valid-1 valid-2 valid-3 valid-4 valid-5 \
 	valid-6 valid-7 valid-8 valid-9 valid-10 \
 	valid-11 valid-12 valid-13 valid-14 valid-15 \

glib/tests/markups/fail-52.expected

+ERROR Error on line 1 char 5: Odd character “\xfc”, expected a “=” after attribute name “r” of element “”

glib/tests/markups/fail-52.gmarkup

+<	r 
\ No newline at end of file

glib/tests/markups/fail-53.expected

+ELEMENT 'r'
+ERROR Error on line 1 char 4: Odd character “\xfc”, expected a “>” character to end the empty-element tag “r”

glib/tests/markups/fail-53.gmarkup

+<r/
\ No newline at end of file