Remove redundant const qualifliers from string_view

	* include/experimental/string_view (basic_string_view::_S_compare):
	Remove redundant const from return type.
	* include/std/string_view (basic_string_view:_S_compare): Likewise.

From-SVN: r240981

libstdc++-v3/ChangeLog

 2016-10-11  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/experimental/string_view (basic_string_view::_S_compare):
+	Remove redundant const from return type.
+	* include/std/string_view (basic_string_view:_S_compare): Likewise.
+
 	* include/bits/std_mutex.h (mutex::native_handle)
 	(lock_guard(mutex_type&, adopt_lock_t)
 	(unique_lock(mutex_type&, adopt_lock_t): Add noexcept.

libstdc++-v3/include/experimental/string_view

@@ -420,7 +420,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     private:
 
-      static constexpr const int
+      static constexpr int
       _S_compare(size_type __n1, size_type __n2) noexcept
       {
 	return difference_type{__n1 - __n2} > std::numeric_limits<int>::max()

libstdc++-v3/include/std/string_view

@@ -414,7 +414,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       
     private:
 
-      static constexpr const int
+      static constexpr int
       _S_compare(size_type __n1, size_type __n2) noexcept
       {
 	return difference_type{__n1 - __n2} > std::numeric_limits<int>::max()