Remove unused <exception> header from <utility>

This header was needed for the declaration of std::terminate but the
calls to it were removed in r242401.

	* include/std/utility: Remove unused <exception> header.

From-SVN: r261749

libstdc++-v3/ChangeLog

+2018-06-19  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/utility: Remove unused <exception> header.
+
 2018-06-18  Jonathan Wakely  <jwakely@redhat.com>
 
 	LWG 2975 ensure construct(pair<T,U>*, ...) used to construct pairs

libstdc++-v3/include/std/utility

@@ -75,10 +75,6 @@
 #include <bits/move.h>
 #include <initializer_list>
 
-#if __cplusplus > 201402L
-#include <exception>
-#endif
-
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION