[libFuzzer] Create single template for visiting Inline8bitCounters

Summary:
Created IterateInline8bitCounters, a single template for visiting  Inline8bitCounters (nested for loop)
Made InitializeUnstableCounters and UpdateUnstableCounters both send a lambda to IterateInline8bitCounters.

Patch by Kyungtak Woo (@kevinwkt).

Reviewers: Dor1s, metzman, kcc, morehouse

Reviewed By: metzman, morehouse

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D49453

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@337403 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerTracePC.h b/FuzzerTracePC.h
index 416b284..d9a427c 100644
--- a/FuzzerTracePC.h
+++ b/FuzzerTracePC.h
@@ -178,6 +178,9 @@
   Set<uintptr_t> ObservedPCs;
   Set<uintptr_t> ObservedFuncs;
 
+  template <class Callback>
+  void IterateInline8bitCounters(Callback CB) const;
+
   std::pair<size_t, size_t> FocusFunction = {-1, -1};  // Module and PC IDs.
 
   ValueBitMap ValueProfileMap;