PPC: Move hash code from hidden string to a private symbol

src/ppc/macro-assembler-ppc.cc

Index: src/ppc/macro-assembler-ppc.cc
diff --git a/src/ppc/macro-assembler-ppc.cc b/src/ppc/macro-assembler-ppc.cc
index e075c170145d40c92ff99b1d765986e926294b5f..40b111649b93eb28b37440f6a0416c732e546c2c 100644
--- a/src/ppc/macro-assembler-ppc.cc
+++ b/src/ppc/macro-assembler-ppc.cc
@@ -1222,6 +1222,8 @@ void MacroAssembler::GetNumberHash(Register t0, Register scratch) {
   // hash = hash ^ (hash >> 16);
   srwi(scratch, t0, Operand(16));
   xor_(t0, t0, scratch);
+  // hash & 0x3fffffff
+  ExtractBitRange(t0, t0, 29, 0);
 }