[turbofan] Factor C call descriptor building into compiler/c-linkage.cc.

src/compiler/arm64/linkage-arm64.cc

Index: src/compiler/arm64/linkage-arm64.cc
diff --git a/src/compiler/arm64/linkage-arm64.cc b/src/compiler/arm64/linkage-arm64.cc
index a82b8c8450a61ad70ec3d68fe6bb4c84672e37ad..1a390ea05c94d225a78408db58d7b4ca9b4b5a76 100644
--- a/src/compiler/arm64/linkage-arm64.cc
+++ b/src/compiler/arm64/linkage-arm64.cc
@@ -21,23 +21,6 @@ struct Arm64LinkageHelperTraits {
   static Register InterpreterDispatchTableReg() { return x20; }
   static Register RuntimeCallFunctionReg() { return x1; }
   static Register RuntimeCallArgCountReg() { return x0; }
-  static RegList CCalleeSaveRegisters() {
-    return (1 << x19.code()) | (1 << x20.code()) | (1 << x21.code()) |
-           (1 << x22.code()) | (1 << x23.code()) | (1 << x24.code()) |
-           (1 << x25.code()) | (1 << x26.code()) | (1 << x27.code()) |
-           (1 << x28.code()) | (1 << x29.code()) | (1 << x30.code());
-  }
-  static RegList CCalleeSaveFPRegisters() {
-    return (1 << d8.code()) | (1 << d9.code()) | (1 << d10.code()) |
-           (1 << d11.code()) | (1 << d12.code()) | (1 << d13.code()) |
-           (1 << d14.code()) | (1 << d15.code());
-  }
-  static Register CRegisterParameter(int i) {
-    static Register register_parameters[] = {x0, x1, x2, x3, x4, x5, x6, x7};
-    return register_parameters[i];
-  }
-  static int CRegisterParametersLength() { return 8; }
-  static int CStackBackingStoreLength() { return 0; }
 };
 
 
@@ -68,12 +51,6 @@ CallDescriptor* Linkage::GetStubCallDescriptor(
 }
 
 
-CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
-                                                  const MachineSignature* sig) {
-  return LH::GetSimplifiedCDescriptor(zone, sig);
-}
-
-
 CallDescriptor* Linkage::GetInterpreterDispatchDescriptor(Zone* zone) {
   return LH::GetInterpreterDispatchDescriptor(zone);
 }