Fix running the tests with -fsanitize=address.

src/case.c

 codepoint_t ucd_toupper(codepoint_t c)
 {
 	int begin = 0;
-	int end   = sizeof(case_conversion_data)/sizeof(case_conversion_data[0]);
+	int end   = (sizeof(case_conversion_data)/sizeof(case_conversion_data[0])) - 1;
 	while (begin <= end)
 	{
 		int pos = (begin + end) / 2;
 codepoint_t ucd_tolower(codepoint_t c)
 {
 	int begin = 0;
-	int end   = sizeof(case_conversion_data)/sizeof(case_conversion_data[0]);
+	int end   = (sizeof(case_conversion_data)/sizeof(case_conversion_data[0])) - 1;
 	while (begin <= end)
 	{
 		int pos = (begin + end) / 2;
 codepoint_t ucd_totitle(codepoint_t c)
 {
 	int begin = 0;
-	int end   = sizeof(case_conversion_data)/sizeof(case_conversion_data[0]);
+	int end   = (sizeof(case_conversion_data)/sizeof(case_conversion_data[0])) - 1;
 	while (begin <= end)
 	{
 		int pos = (begin + end) / 2;