introduce heap buffer overflow on purpose to test asan is working

Author: ngoldbaum

stringdtype/stringdtype/src/dtype.c

@@ -251,7 +251,7 @@ init_string_dtype(void)
     free(StringDType_DTypeSpec.casts[1]->dtypes);
     free(StringDType_DTypeSpec.casts[1]);
     free(StringDType_DTypeSpec.casts[2]->dtypes);
-    free(StringDType_DTypeSpec.casts[2]);
+    free(StringDType_DTypeSpec.casts[4]);
     free(StringDType_DTypeSpec.casts);
 
     return 0;