Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/src/debug/arm64/debug-arm64.cc b/src/debug/arm64/debug-arm64.cc
index c2b60a9..3e4b67c 100644
--- a/src/debug/arm64/debug-arm64.cc
+++ b/src/debug/arm64/debug-arm64.cc
@@ -74,6 +74,10 @@
   patcher.blr(ip0);
 }
 
+bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
+  Instruction* current_instr = reinterpret_cast<Instruction*>(pc);
+  return !current_instr->IsNop(Assembler::DEBUG_BREAK_NOP);
+}
 
 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
                                           DebugBreakCallHelperMode mode) {