PPC/s390: [regexp] Port RegExpExecStub to CSA (mostly)

src/s390/code-stubs-s390.cc

Index: src/s390/code-stubs-s390.cc
diff --git a/src/s390/code-stubs-s390.cc b/src/s390/code-stubs-s390.cc
index c157b98f2876bb5eae63c6bb213ab0dff9ca7fda..08f376862b83cc8cc568cff7874b46282b438075 100644
--- a/src/s390/code-stubs-s390.cc
+++ b/src/s390/code-stubs-s390.cc
@@ -1281,7 +1281,7 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   CHECK(r2.is(RegExpExecDescriptor::StringRegister()));
 
   // Locate the code entry and call it.
-  Register code_reg = RegExpDescriptor::CodeRegister();
+  Register code_reg = RegExpExecDescriptor::CodeRegister();
   __ AddP(code_reg, Operand(Code::kHeaderSize - kHeapObjectTag));
 
   DirectCEntryStub stub(isolate());