[RISCV] Legalize G_CTLZ/G_CTLZ_ZERO_UNDEF/G_CTTZ/G_CTTZ_ZERO_UNDEF.

The base ISA does not support these operations. A future patch
will enable them for Zbb.

Author: topperc

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

@@ -89,7 +89,7 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
       .maxScalar(0, sXLen)
       .lower();
 
-  getActionDefinitionsBuilder(G_CTPOP)
+  getActionDefinitionsBuilder({G_CTPOP, G_CTLZ, G_CTLZ_ZERO_UNDEF, G_CTTZ, G_CTTZ_ZERO_UNDEF})
       .maxScalar(0, sXLen)
       .scalarSameSizeAs(1, 0)
       .lower();