Add tests of the parsing of the --object-bits argument

In order to ensure that this functionality is not broken by subsequent
refactorings.

Author: thomasspriggs

regression/cbmc/object-bits-parsing/non_numeric.desc

@@ -0,0 +1,9 @@
+CORE
+test.c
+--object-bits foobar
+object-bits must be positive and less than the pointer width
+^EXIT=1$
+^SIGNAL=0$
+--
+--
+Test parsing of an invalid non numeric object-bits setting.

regression/cbmc/object-bits-parsing/test.c

@@ -0,0 +1,8 @@
+
+#include <assert.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+  void *p = malloc(1);
+}

regression/cbmc/object-bits-parsing/too_large.desc

@@ -0,0 +1,9 @@
+CORE
+test.c
+--object-bits 65
+object-bits must be positive and less than the pointer width
+^EXIT=1$
+^SIGNAL=0$
+--
+--
+Test parsing of a too large object-bits setting.

regression/cbmc/object-bits-parsing/valid.desc

@@ -0,0 +1,8 @@
+CORE
+test.c
+--object-bits 8
+^EXIT=0$
+^SIGNAL=0$
+--
+--
+Test parsing of a valid object-bits setting.

regression/cbmc/object-bits-parsing/zero.desc

@@ -0,0 +1,9 @@
+CORE
+test.c
+--object-bits 0
+object-bits must be positive and less than the pointer width
+^EXIT=1$
+^SIGNAL=0$
+--
+--
+Test parsing of a too small object-bits setting.