[SMTChecker] Adding unary increment and decrement as under/overflow verification targets for the CHC engine

test/libsolidity/smtCheckerTests/array_members/pop_loop_safe.sol

@@ -9,3 +9,5 @@ contract C {
 		}
 	}
 }
+// ----
+// Warning 4984: (112-115): CHC: Overflow (resulting value larger than 2**256 - 1) might happen here.

test/libsolidity/smtCheckerTests/array_members/pop_loop_unsafe.sol

@@ -11,4 +11,5 @@ contract C {
 	}
 }
 // ----
+// Warning 4984: (112-115): CHC: Overflow (resulting value larger than 2**256 - 1) might happen here.
 // Warning 2529: (150-157): CHC: Empty array "pop" happens here.\nCounterexample:\na = []\nl = 0\n\n\nTransaction trace:\nconstructor()\nState: a = []\nf(0)

test/libsolidity/smtCheckerTests/array_members/push_overflow_2_safe_no_overflow_assumption.sol

@@ -11,3 +11,5 @@ contract C {
 		assert(x[0] == 42);
 	}
 }
+// ----
+// Warning 4984: (174-177): CHC: Overflow (resulting value larger than 2**256 - 1) might happen here.