[RISCV]Keep (select c, 0/-1, X) during PerformDAGCombine

D135833, lowerSelect: (select C, -1/0, X) -> or/and
Keep (select c, 0/-1, X), thus making better use of lowerSelect to eliminate branch instructions.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D139272