C++: Improve LossyFunctionResultCast join order

Before on wireshark:
```
Tuple counts for #select#ff@eca61bf2:
        180100  ~2%    {2} r1 = SCAN Type::Type::getUnderlyingType#dispred#f0820431#ff OUTPUT In.1, In.0
            84  ~2%    {2} r2 = JOIN r1 WITH project#Type::FloatingPointType#class#2e8eb3ef#fffff ON FIRST 1 OUTPUT Lhs.1, Rhs.0
          2021  ~0%    {2} r3 = JOIN r2 WITH Function::Function::getType#dispred#f0820431#fb_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1
          2437  ~0%    {2} r4 = JOIN r3 WITH Call::FunctionCall::getTarget#dispred#f0820431#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.1, Rhs.1
          2150  ~0%    {2} r5 = r4 AND NOT LossyFunctionResultCast::whiteListWrapped#377b528a#f(Lhs.1)
          2150  ~0%    {2} r6 = SCAN r5 OUTPUT In.1, In.0
           313  ~0%    {3} r7 = JOIN r6 WITH exprconv ON FIRST 1 OUTPUT Rhs.1, Lhs.1, Lhs.0
           313  ~0%    {3} r8 = JOIN r7 WITH Cast::Conversion#class#1f33e835#b ON FIRST 1 OUTPUT Lhs.0, Lhs.1, Lhs.2
           148  ~3%    {2} r9 = JOIN r8 WITH Expr::Expr::isCompilerGenerated#f0820431#b ON FIRST 1 OUTPUT Lhs.2, Lhs.1
           148  ~1%    {3} r10 = JOIN r9 WITH Expr::Expr::getActualType#dispred#f0820431#bf ON FIRST 1 OUTPUT Rhs.1, Lhs.1, Lhs.0
            21  ~0%    {3} r11 = JOIN r10 WITH Type::IntegralType#class#2e8eb3ef#ff ON FIRST 1 OUTPUT Lhs.1, Lhs.2, Lhs.0
            21  ~0%    {3} r12 = JOIN r11 WITH Element::ElementBase::toString#dispred#f0820431#ff ON FIRST 1 OUTPUT Lhs.2, Lhs.1, Rhs.1
            21  ~0%    {2} r13 = JOIN r12 WITH Element::ElementBase::toString#dispred#f0820431#ff ON FIRST 1 OUTPUT Lhs.1, ("Return value of type " ++ Lhs.2 ++ " is implicitly converted to " ++ Rhs.1 ++ " here.")
                       return r13
```

After:
```
Tuple counts for #select#ff@a5a185eg:
          20  ~0%    {2} r1 = SCAN project#Type::FloatingPointType#class#2e8eb3ef#fffff OUTPUT In.0, In.0
          20  ~0%    {2} r2 = JOIN r1 WITH project#Type::FloatingPointType#class#2e8eb3ef#fffff ON FIRST 1 OUTPUT Lhs.1, Lhs.0
          84  ~2%    {2} r3 = JOIN r2 WITH Type::Type::getUnderlyingType#dispred#f0820431#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1
        2021  ~0%    {2} r4 = JOIN r3 WITH Function::Function::getType#dispred#f0820431#fb_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1
        2437  ~0%    {2} r5 = JOIN r4 WITH Call::FunctionCall::getTarget#dispred#f0820431#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.1, Rhs.1
        2150  ~0%    {2} r6 = r5 AND NOT LossyFunctionResultCast::whiteListWrapped#377b528a#f(Lhs.1)
        2150  ~0%    {2} r7 = SCAN r6 OUTPUT In.1, In.0
         313  ~0%    {3} r8 = JOIN r7 WITH exprconv ON FIRST 1 OUTPUT Rhs.1, Lhs.1, Lhs.0
         313  ~0%    {3} r9 = JOIN r8 WITH Cast::Conversion#class#1f33e835#b ON FIRST 1 OUTPUT Lhs.0, Lhs.1, Lhs.2
         148  ~3%    {2} r10 = JOIN r9 WITH Expr::Expr::isCompilerGenerated#f0820431#b ON FIRST 1 OUTPUT Lhs.2, Lhs.1
         148  ~1%    {3} r11 = JOIN r10 WITH Expr::Expr::getActualType#dispred#f0820431#bf ON FIRST 1 OUTPUT Rhs.1, Lhs.1, Lhs.0
          21  ~0%    {3} r12 = JOIN r11 WITH Type::IntegralType#class#2e8eb3ef#ff ON FIRST 1 OUTPUT Lhs.1, Lhs.2, Lhs.0
          21  ~0%    {3} r13 = JOIN r12 WITH Element::ElementBase::toString#dispred#f0820431#ff ON FIRST 1 OUTPUT Lhs.2, Lhs.1, Rhs.1
          21  ~0%    {2} r14 = JOIN r13 WITH Element::ElementBase::toString#dispred#f0820431#ff ON FIRST 1 OUTPUT Lhs.1, ("Return value of type " ++ Lhs.2 ++ " is implicitly converted to " ++ Rhs.1 ++ " here.")
                     return r14
```

Author: jketema

cpp/ql/src/Likely Bugs/Conversion/LossyFunctionResultCast.ql

@@ -44,7 +44,7 @@ predicate whiteListWrapped(FunctionCall fc) {
 
 from FunctionCall c, FloatingPointType t1, IntegralType t2
 where
-  t1 = c.getTarget().getType().getUnderlyingType() and
+  pragma[only_bind_into](t1) = c.getTarget().getType().getUnderlyingType() and
   t2 = c.getActualType() and
   c.hasImplicitConversion() and
   not whiteListWrapped(c)