removed superfluous declarations from header files

Summary:
Clang doesn't like the same member of a class being defined more than once,
or default argument values being defined more than once. This diff removes some
instances.

@override-unit-failures

Test Plan: Compiled the code with Clang and GCC

Reviewed By: andrewjcg@fb.com

FB internal diff: D913226

folly/Range.h

@@ -43,17 +43,6 @@ namespace folly {
 
 template <class T> class Range;
 
-/**
- * Finds the first occurrence of needle in haystack. The algorithm is on
- * average faster than O(haystack.size() * needle.size()) but not as fast
- * as Boyer-Moore. On the upside, it does not do any upfront
- * preprocessing and does not allocate memory.
- */
-template <class T, class Comp = std::equal_to<typename Range<T>::value_type>>
-inline size_t qfind(const Range<T> & haystack,
-                    const Range<T> & needle,
-                    Comp eq = Comp());
-
 /**
  * Finds the first occurrence of needle in haystack. The result is the
  * offset reported to the beginning of haystack, or string::npos if
@@ -565,7 +554,10 @@ struct StringPieceHash {
 };
 
 /**
- * Finds substrings faster than brute force by borrowing from Boyer-Moore
+ * Finds the first occurrence of needle in haystack. The algorithm is on
+ * average faster than O(haystack.size() * needle.size()) but not as fast
+ * as Boyer-Moore. On the upside, it does not do any upfront
+ * preprocessing and does not allocate memory.
  */
 template <class T, class Comp>
 size_t qfind(const Range<T>& haystack,

folly/dynamic.h

@@ -443,7 +443,6 @@ public:
 private:
   friend struct TypeError;
   struct ObjectImpl;
-  struct ObjectMaker;
   template<class T> struct TypeInfo;
   template<class T> struct CompareOp;
   template<class T> struct GetAddrImpl;