Implement UnalignedLoad and UnalignedStore in WASM using LoadByte/Shift/Or and StoreByte/Shift/And.

src/compiler/ppc/instruction-selector-ppc.cc

Index: src/compiler/ppc/instruction-selector-ppc.cc
diff --git a/src/compiler/ppc/instruction-selector-ppc.cc b/src/compiler/ppc/instruction-selector-ppc.cc
index b8ca3ba692ac1f537e249984a191075eaf405389..1bc9637e1055f6928550baeb56bda6a3b99038ee 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -1991,6 +1991,13 @@ InstructionSelector::SupportedMachineOperatorFlags() {
   // We omit kWord32ShiftIsSafe as s[rl]w use 0x3f as a mask rather than 0x1f.
 }
 
+// static
+MachineOperatorBuilder::AlignmentRequirements
+InstructionSelector::AlignmentRequirements() {
+  return MachineOperatorBuilder::AlignmentRequirements::
+      FullUnalignedAccessSupport();
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8