C++: Inline a predicate that contains CPs

The `overflows` predicate had quite severe Cartesian products. We didn't
see them in practice because magic saved us, but we can't rely on magic
in the future, so it seems better to inline this predicate.

Tuple counts and speed look good both before and after.

Author: jbj

cpp/ql/src/Likely Bugs/Arithmetic/IntMultToLong.ql

@@ -166,6 +166,7 @@ class VarAnalyzableExpr extends AnalyzableExpr, VariableAccess {
  * Holds if `t` is not an instance of `IntegralType`,
  * or if `me` cannot be proven to not overflow
  */
+pragma[inline]
 predicate overflows(MulExpr me, Type t) {
   t instanceof IntegralType
   implies