deps: V8: cherry-pick 0a055086c377

Original commit message:

    PPC: Using a scratch register under LoadRealStackLimit

    Change-Id: Id9e9142a8ff185309b91dcfff70dae8ccf8b5166
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1954244
    Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
    Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
    Cr-Commit-Position: refs/heads/master@{#65357}

Refs: v8/v8@0a05508
PR-URL: #30109
Reviewed-By: Myles Borins <myles.borins@gmail.com>

common.gypi

@@ -38,7 +38,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.14',
+    'v8_embedder_string': '-node.15',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/src/builtins/ppc/builtins-ppc.cc

@@ -90,7 +90,7 @@ void LoadRealStackLimit(MacroAssembler* masm, Register destination) {
   intptr_t offset =
       TurboAssembler::RootRegisterOffsetForExternalReference(isolate, limit);
   CHECK(is_int32(offset));
-  __ LoadP(destination, MemOperand(kRootRegister, offset));
+  __ LoadP(destination, MemOperand(kRootRegister, offset), r0);
 }
 
 void Generate_StackOverflowCheck(MacroAssembler* masm, Register num_args,