Avoid reserved identifier in include/parallel/multiway_merge.h

	* include/parallel/multiway_merge.h (_RAIter3): Replace _C by _Cp.

From-SVN: r276515

libstdc++-v3/ChangeLog

+2019-10-03  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* include/parallel/multiway_merge.h (_RAIter3): Replace _C by _Cp.
+
 2019-10-02  Jonathan Wakely  <jwakely@redhat.com>
 
 	* config/abi/pre/gnu.ver: Tighten up greedy wildcards.

libstdc++-v3/include/parallel/multiway_merge.h

@@ -232,7 +232,7 @@ namespace __gnu_parallel
    *
    * @return End iterator of output sequence.
    */
-  template<template<typename _RAI, typename _C> class iterator,
+  template<template<typename _RAI, typename _Cp> class iterator,
            typename _RAIterIterator,
            typename _RAIter3,
            typename _DifferenceTp,
@@ -351,7 +351,7 @@ namespace __gnu_parallel
    *
    * @return End iterator of output sequence.
    */
-  template<template<typename _RAI, typename _C> class iterator,
+  template<template<typename _RAI, typename _Cp> class iterator,
            typename _RAIterIterator,
            typename _RAIter3,
            typename _DifferenceTp,