Add regression test for interaction of volatile/non-volatile variables

Author: danpoe

regression/goto-instrument/nondet-volatile-04/test.c

@@ -0,0 +1,10 @@
+#include <assert.h>
+
+volatile int x;
+int y;
+
+void main()
+{
+  y = x;
+  assert(x == y);
+}

regression/goto-instrument/nondet-volatile-04/test.desc

@@ -0,0 +1,9 @@
+CORE
+test.c
+--nondet-volatile
+^\[main.assertion.1\] line \d+ assertion x == y: FAILURE$
+^EXIT=10$
+^SIGNAL=0$
+--
+--
+Check interaction between a volatile and a non-volatile variable