[gcc r11-9927] libstdc++: Remove workaround for FE bug in std::tuple [PR96592]

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:d65b274f1f44c59382b7dad7759cfaf3c8397cf8

commit r11-9927-gd65b274f1f44c59382b7dad7759cfaf3c8397cf8
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Nov 26 17:46:47 2021 +0000

    libstdc++: Remove workaround for FE bug in std::tuple [PR96592]
    
    The FE bug was fixed, so we don't need this workaround now.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/96592
            * include/std/tuple (tuple::is_constructible): Remove.
    
    (cherry picked from commit 76c6be48b7841524974754f8ea7533b82c7de77e)

Diff:
---
 libstdc++-v3/include/std/tuple | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index dcf30bd9a8d..63bd68fbe43 100644
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -553,10 +553,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<bool, typename... _Types>
     struct _TupleConstraints
     {
-      template<typename _Tp, typename _Up> // Workaround for PR 96592
-	using is_constructible
-	  = __bool_constant<__is_constructible(_Tp, _Up)>;
-
       // Constraint for a non-explicit constructor.
       // True iff each Ti in _Types... can be constructed from Ui in _UTypes...
       // and every Ui is implicitly convertible to Ti.