[test/unicode] Fix double-free

Caught by "make check-valgrind".

test/Makefile.am

@@ -102,7 +102,7 @@ valgrind_verbose = $(valgrind_verbose_$(V))
 valgrind_verbose_ = $(valgrind_verbose_$(AM_DEFAULT_VERBOSITY))
 valgrind_verbose_0 = | \
 	grep '\(^[^=]\|ERROR SUMMARY\|definitely lost\|indirectly lost\)' | grep -v ': 0'
-
+# TODO: The following check does not fail if valgrind finds error.  It should.
 check-valgrind:
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLGS) check-tool TOOL="valgrind $(VALGRIND_FLAGS)" \
 	2>&1 | tee valgrind-log $(valgrind_verbose)

test/test-unicode.c

@@ -633,8 +633,6 @@ test_unicode_setters (void)
     g_assert (data[0].freed && !data[1].freed);
     hb_unicode_funcs_destroy (uf);
     g_assert (data[0].freed && !data[1].freed);
-
-    hb_unicode_funcs_destroy (uf);
   }
 }