Extend test to cover negative integrals

In order to confirm that there is no negative number related bug.

Author: thomasspriggs

regression/cbmc/integral-trace/test.c

@@ -12,6 +12,11 @@ int main()
   int32_t i3 = 4;
   int64_t i4 = 5;
 
+  int8_t in1 = -2;
+  int16_t in2 = -3;
+  int32_t in3 = -4;
+  int64_t in4 = -5;
+
   uint8_t u8 = 'a';
   uint16_t u16 = 8;
   uint32_t u32 = 16;

regression/cbmc/integral-trace/test.desc

@@ -13,6 +13,10 @@ VERIFICATION FAILED
 <full_lhs>i2</full_lhs>\n\s*<full_lhs_value binary="0{14}11">3</full_lhs_value>
 <full_lhs>i3</full_lhs>\n\s*<full_lhs_value binary="0{29}100">4</full_lhs_value>
 <full_lhs>i4</full_lhs>\n\s*<full_lhs_value binary="0{61}101">5l</full_lhs_value>
+<full_lhs>in1</full_lhs>\n\s*<full_lhs_value binary="1{6}10">-2</full_lhs_value>
+<full_lhs>in2</full_lhs>\n\s*<full_lhs_value binary="1{14}01">-3</full_lhs_value>
+<full_lhs>in3</full_lhs>\n\s*<full_lhs_value binary="1{29}100">-4</full_lhs_value>
+<full_lhs>in4</full_lhs>\n\s*<full_lhs_value binary="1{61}011">-5l</full_lhs_value>
 --
 --
 Checks that the binary value is printed for integral types.