[RISCV][GISEL] Legalize G_ICMP for scalable vector types

The result of a vector G_ICMP is a vector with an s1 element type. The
input vectors can be integer, floating-point, or boolean element type.

Author: michaelmaitland

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

@@ -242,7 +242,9 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
 
   getActionDefinitionsBuilder(G_ICMP)
       .legalFor({{sXLen, sXLen}, {sXLen, p0}})
-      .widenScalarToNextPow2(1)
+      .legalIf(all(typeIsLegalBoolVec(0, BoolVecTys, ST),
+                   typeIsLegalIntOrFPVec(1, IntOrFPVecTys, ST)))
+      .widenScalarOrEltToNextPow2OrMinSize(1, 8)
       .clampScalar(1, sXLen, sXLen)
       .clampScalar(0, sXLen, sXLen);