Add KNOWBUG test for 5093

Author: yumibagge

regression/cbmc/pointer-to-struct-with-flexible-array-member-as-parameter-to-entry-point/main.c

@@ -0,0 +1,9 @@
+typedef struct ST
+{
+  int id;
+  int c[];
+} ST;
+
+void testFunc(ST **t)
+{
+}

regression/cbmc/pointer-to-struct-with-flexible-array-member-as-parameter-to-entry-point/test.desc

@@ -0,0 +1,10 @@
+KNOWNBUG
+main.c
+--function testFunc
+--
+^EXIT=0$
+^SIGNAL=0$
+--
+^EXIT=134$
+--
+Github issue #5093: Pointer to struct with flexible array member as parameter to entry point causes invariant violation