PPC/s390: [wasm][liftoff] Emit safepoints for externref values on the stack

Port 10348e8e

Original Commit Message:

    With this CL we emit safepoint maps for externref values on the Liftoff
    value stack. With that there is support for externref parameters and
    locals in Liftoff, as well as for intermediate values of type
    externref.

R=ahaas@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I369c0e2e7fb1c4681101a149b01e1a9580051d45
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2398845Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#69747}

src/wasm/baseline/ppc/liftoff-assembler-ppc.h

@@ -80,13 +80,7 @@ int LiftoffAssembler::SlotSizeForType(ValueType type) {
 }
 
 bool LiftoffAssembler::NeedsAlignment(ValueType type) {
-  switch (type.kind()) {
-    case ValueType::kS128:
-      return true;
-    default:
-      // No alignment because all other types are kStackSlotSize.
-      return false;
-  }
+  return (type.kind() == ValueType::kS128 || type.is_reference_type());
 }
 
 void LiftoffAssembler::LoadConstant(LiftoffRegister reg, WasmValue value,

src/wasm/baseline/s390/liftoff-assembler-s390.h

@@ -79,13 +79,7 @@ int LiftoffAssembler::SlotSizeForType(ValueType type) {
 }
 
 bool LiftoffAssembler::NeedsAlignment(ValueType type) {
-  switch (type.kind()) {
-    case ValueType::kS128:
-      return true;
-    default:
-      // No alignment because all other types are kStackSlotSize.
-      return false;
-  }
+  return (type.kind() == ValueType::kS128 || type.is_reference_type());
 }
 
 void LiftoffAssembler::LoadConstant(LiftoffRegister reg, WasmValue value,