Implement CFI for Quick.

CFI is necessary for stack unwinding in gdb, lldb, and libunwind.

Change-Id: Ic3b84c9dc91c4bae80e27cda02190f3274e95ae8
diff --git a/compiler/dwarf/debug_frame_opcode_writer.h b/compiler/dwarf/debug_frame_opcode_writer.h
index cc4ef8f..85186bb 100644
--- a/compiler/dwarf/debug_frame_opcode_writer.h
+++ b/compiler/dwarf/debug_frame_opcode_writer.h
@@ -150,7 +150,7 @@
   }
 
   void RememberState() {
-    // Note that we do not need to advance the PC.
+    ImplicitlyAdvancePC();
     this->PushUint8(DW_CFA_remember_state);
   }
 
@@ -236,6 +236,10 @@
     this->PushData(expr, expr_size);
   }
 
+  int GetCurrentPC() const {
+    return current_pc_;
+  }
+
   int GetCurrentCFAOffset() const {
     return current_cfa_offset_;
   }