[CodeGen][X86][NFC] Copy two selectcc tests from AArch64.

These tests are for DAGCombiner::foldSelectCCToShiftAnd().
Right now, they were only tested for AArch64,
but given the upcoming X86 changes to the hasAndNot(),
the test coverage needs to be added.

These tests originated from D27489 / rL289738

llvm-svn: 331454