[gcc r11-8527] [libstdc++] Remove unused hasher instance.

[Thomas Rodgers]

https://gcc.gnu.org/g:7976eccf5fe2796f4035de44a607ebd29d57e108

commit r11-8527-g7976eccf5fe2796f4035de44a607ebd29d57e108
Author: Thomas Rodgers <rodgert@appliantology.com>
Date:   Tue Jun 8 15:41:31 2021 -0700

    [libstdc++] Remove unused hasher instance.
    
    This is a remnant of poorly executed refactoring.
    
    libstdc++-v3/ChangeLog:
    
            * include/std/barrier (__tree_barrier::_M_arrive): Remove
            unnecessary hasher instantiation.
    
    (cherry picked from commit 16a8e18858abdc877b14caf33dec24aada1a3308)

Diff:
---
 libstdc++-v3/include/std/barrier | 1 -
 1 file changed, 1 deletion(-)

diff --git a/libstdc++-v3/include/std/barrier b/libstdc++-v3/include/std/barrier
index fd61fb4f9da..4210e30d1ce 100644
--- a/libstdc++-v3/include/std/barrier
+++ b/libstdc++-v3/include/std/barrier
@@ -103,7 +103,6 @@ It looks different from literature pseudocode for two main reasons:
 			   static_cast<__barrier_phase_t>(__old_phase_val + 2);
 
 	size_t __current_expected = _M_expected;
-	std::hash<std::thread::id> __hasher;
 	__current %= ((_M_expected + 1) >> 1);
 
 	for (int __round = 0; ; ++__round)