ARM64: improve Adr patching

src/arm64/assembler-arm64.h

Index: src/arm64/assembler-arm64.h
diff --git a/src/arm64/assembler-arm64.h b/src/arm64/assembler-arm64.h
index a92be4b8689df39bb25e3a955f184a5327415927..a2ab4cd09f88a3971fae5cadf739f531749ea261 100644
--- a/src/arm64/assembler-arm64.h
+++ b/src/arm64/assembler-arm64.h
@@ -2286,13 +2286,10 @@ class PatchingAssembler : public Assembler {
     CpuFeatures::FlushICache(buffer_, length);
   }
 
-  static const int kMovInt64NInstrs = 4;
-  void MovInt64(const Register& rd, int64_t imm);
-
   // See definition of PatchAdrFar() for details.
-  static const int kAdrFarPatchableNNops = kMovInt64NInstrs - 1;
-  static const int kAdrFarPatchableNInstrs = kAdrFarPatchableNNops + 3;
-  void PatchAdrFar(Instruction* target);
+  static const int kAdrFarPatchableNNops = 2;
+  static const int kAdrFarPatchableNInstrs = kAdrFarPatchableNNops + 2;
+  void PatchAdrFar(ptrdiff_t target_offset);
 };