[InstSimplify] (x | y) & (x | !y) --> x

https://alive2.llvm.org/ce/z/QagQMn

This fold is handled by instcombine via SimplifyUsingDistributiveLaws(),
but we are missing the sibliing fold for 'logical and' (implemented with
'select'). Retrofitting the code in instcombine looks much harder
than just adding a small adjustment here, and this is potentially more
efficient and beneficial to other passes.