Added a regression test for SMT encoding of struct

Author: SaswatPadhi

regression/cbmc/struct15/main.c

@@ -0,0 +1,14 @@
+#include <assert.h>
+
+struct test
+{
+  unsigned int a;
+  unsigned int b;
+};
+
+int main()
+{
+  struct test t;
+  if(t.a > 10)
+    assert(t.a > 0);
+}

regression/cbmc/struct15/test.desc

@@ -0,0 +1,11 @@
+CORE
+main.c
+--trace --smt2
+^EXIT=0$
+^SIGNAL=0$
+^VERIFICATION SUCCESSFUL$
+--
+^map::at:
+key not found
+--
+This test checks the encoding of C `struct`s using SMT2 data types.