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

src/compiler/arm/linkage-arm.cc

Index: src/compiler/arm/linkage-arm.cc
diff --git a/src/compiler/arm/linkage-arm.cc b/src/compiler/arm/linkage-arm.cc
index e3cd98290ff6104ffaf4f8c39b58ee462b023538..69d1e35097b79813d645b5022c371e51f3be6549 100644
--- a/src/compiler/arm/linkage-arm.cc
+++ b/src/compiler/arm/linkage-arm.cc
@@ -21,21 +21,6 @@ struct ArmLinkageHelperTraits {
   static Register InterpreterDispatchTableReg() { return r8; }
   static Register RuntimeCallFunctionReg() { return r1; }
   static Register RuntimeCallArgCountReg() { return r0; }
-  static RegList CCalleeSaveRegisters() {
-    return r4.bit() | r5.bit() | r6.bit() | r7.bit() | r8.bit() | r9.bit() |
-           r10.bit();
-  }
-  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[] = {r0, r1, r2, r3};
-    return register_parameters[i];
-  }
-  static int CRegisterParametersLength() { return 4; }
-  static int CStackBackingStoreLength() { return 0; }
 };
 
 
@@ -66,12 +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);
 }