[lanai] Manually match 0/-1 with R0/R1.

Summary: Previously 0 and -1 was matched via tablegen rules. But this could cause problems where a physical register was being used where a virtual register was expected (seen in optimizeSelect and TwoAddressInstructionPass). Instead follow AArch64 and match in DAGToDAGISel.

Reviewers: eliben, majnemer

Subscribers: llvm-commits, aemerson

Differential Revision: https://reviews.llvm.org/D27171

llvm-svn: 288215