Correcting test and adding to the suite

The known bug related to this issue was checking the output was wrong,
so made it check the correct output. Since it is now fixed, swapped it
from KNOWNBUG to CORE.

Author: thk123

regression/goto-instrument/const-struct1/test.desc

@@ -1,7 +1,7 @@
-KNOWNBUG
+CORE
 main.c
 --show-symbol-table
-^Type\.*: struct struct_tag_name$
+^Type\.*: const struct struct_tag_name$
 ^Type\.*: const double$
 ^EXIT=0$
 ^SIGNAL=0$