[SimplifyCFG] FoldTwoEntryPHINode(): bailout on inverted logical and/or (PR51149)

The logical (select) form of and/or will now be a source of problems.
We don't really account for it's inverted form, yet it exists,
and presumably we should treat it just like non-inverted form:
https://alive2.llvm.org/ce/z/BU9AXk

https://bugs.llvm.org/show_bug.cgi?id=51149 reports a reportedly-serious
perf regression that will hopefully be mitigated by this.