folly/test/RangeFindBenchmark.cpp: avoid shadowing warning: rename inner "n": s/\<n\>/c/

Reviewed By: yfeldblum

Differential Revision: D4120553

fbshipit-source-id: 87c202232bcfabeff7eb62a8133b9b5577b09cbc

folly/test/RangeFindBenchmark.cpp

@@ -139,13 +139,13 @@ template <class Func>
 void countHits(Func func, size_t n) {
   StringPiece needles = "\r\n\1";
   FOR_EACH_RANGE (i, 0, n) {
-    size_t p, n = 0;
+    size_t p, c = 0;
     for (StringPiece left = file;
          (p = func(left, needles)) != StringPiece::npos;
          left.advance(p + 1)) {
-      ++n;
+      ++c;
     }
-    doNotOptimizeAway(n);
+    doNotOptimizeAway(c);
   }
 }