PPC: [Interpreter] Fix PushArgsAndConstruct

Port 48a3227b

Original commit message:
    When reserving a stack slot for the receiver, push an Immediate(0)
    rather than a register that contains an untagged integer.
    All other platforms push zero already.

R=jkummerow@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1588053003

Cr-Commit-Position: refs/heads/master@{#33314}

src/ppc/builtins-ppc.cc

@@ -1013,7 +1013,8 @@ void Builtins::Generate_InterpreterPushArgsAndConstruct(MacroAssembler* masm) {
   // -----------------------------------
 
   // Push a slot for the receiver to be constructed.
-  __ push(r3);
+  __ li(r0, Operand::Zero());
+  __ push(r0);
 
   // Push the arguments (skip if none).
   Label skip;