Fix smog2 muons builders

the smog2_muons_builders build a cut which looks like (PT > something) + MAXSDOCACUT(something) instead of (PT > something) & MAXSDOCACUT(something) which results in taking the 'or' of the two cuts: as soon as one of them is non-zero, then the sum is non-zero, which ends up as true.

This was found as part of fixing another problem, and the fix to that problem prevents the above from compiling, and requires this fix.

The reason this was accepted is that a bool can be implicitly converted to an int, which then allows addition, and an int can be converted into a bool again. The reason this will fail with LHCb!5300 (merged) is that it ensures that the result of a cut using a combination as argument is no longer a bool but a mask (in practice still a single bit) instead, and masks do not define a + operation.