Cleanup String.<init> handling.

Move everything to one place (currently well_known_classes.cc, but
no strong preference) and define a macro to easily handle the list
of affected methods.

test: m test-art-host
test: m test-art-target
Change-Id: Ib8372d130d5458516a1f1ae31014afc76037fc34
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 47dfb2e..c300080 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -4276,10 +4276,13 @@
                                                                   Location temp) {
   Location callee_method = temp;  // For all kinds except kRecursive, callee will be in temp.
   switch (invoke->GetMethodLoadKind()) {
-    case HInvokeStaticOrDirect::MethodLoadKind::kStringInit:
+    case HInvokeStaticOrDirect::MethodLoadKind::kStringInit: {
       // temp = thread->string_init_entrypoint
-      __ fs()->movl(temp.AsRegister<Register>(), Address::Absolute(invoke->GetStringInitOffset()));
+      uint32_t offset =
+          GetThreadOffset<kX86PointerSize>(invoke->GetStringInitEntryPoint()).Int32Value();
+      __ fs()->movl(temp.AsRegister<Register>(), Address::Absolute(offset));
       break;
+    }
     case HInvokeStaticOrDirect::MethodLoadKind::kRecursive:
       callee_method = invoke->GetLocations()->InAt(invoke->GetSpecialInputIndex());
       break;