libstdc++: Remove non-standard feature test macros

These macros were replaced by __cpp_lib_map_try_emplace and
__cpp_lib_unordered_map_try_emplace, because those names are more
descriptive. We've kept both old and new names so far, but I think we
can remove the old ones now.

	* include/bits/stl_map.h (__cpp_lib_map_insertion): Remove old
	macro.
	* include/bits/unordered_map.h (__cpp_lib_unordered_map_insertion):
	Likewise.
	* include/std/version (__cpp_lib_map_insertion)
	(__cpp_lib_unordered_map_insertion): Remove.

libstdc++-v3/ChangeLog

 2020-04-22  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/stl_map.h (__cpp_lib_map_insertion): Remove old
+	macro.
+	* include/bits/unordered_map.h (__cpp_lib_unordered_map_insertion):
+	Likewise.
+	* include/std/version (__cpp_lib_map_insertion)
+	(__cpp_lib_unordered_map_insertion): Remove.
+
 	* include/std/condition_variable (__cpp_lib_jthread): Remove
 	redundant definition.
 	* include/std/stop_token (__cpp_lib_jthread): Update macro value to

libstdc++-v3/include/bits/stl_map.h

@@ -894,7 +894,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	{ _M_t._M_insert_range_unique(__first, __last); }
 
 #if __cplusplus > 201402L
-#define __cpp_lib_map_insertion 201411
       /**
        *  @brief Attempts to insert or assign a std::pair into the %map.
        *  @param __k    Key to use for finding a possibly existing pair in

libstdc++-v3/include/bits/unordered_map.h

@@ -657,7 +657,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
 
 #if __cplusplus > 201402L
-#define __cpp_lib_unordered_map_insertion 201411
       /**
        *  @brief Attempts to insert a std::pair into the %unordered_map.
        *  @param __k    Key to use for finding a possibly existing pair in

libstdc++-v3/include/std/version

@@ -134,7 +134,6 @@
 #define __cpp_lib_invoke 201411L
 #define __cpp_lib_lcm 201606
 #define __cpp_lib_make_from_tuple 201606
-#define __cpp_lib_map_insertion 201411
 #define __cpp_lib_map_try_emplace 201411
 #define __cpp_lib_math_special_functions 201603L
 #ifdef _GLIBCXX_HAS_GTHREADS
@@ -156,7 +155,6 @@
 #define __cpp_lib_shared_ptr_weak_type 201606
 #define __cpp_lib_string_view 201803
 // #define __cpp_lib_to_chars 201611L
-#define __cpp_lib_unordered_map_insertion 201411
 #define __cpp_lib_unordered_map_try_emplace 201411
 #define __cpp_lib_variant 201606L
 #endif