[gcc r16-772] libstdc++: use maintained size when split pb_ds binary search trees

https://gcc.gnu.org/g:36c20fee22d40c6d25f52e929b42f5eab62cb1eb commit r16-772-g36c20fee22d40c6d25f52e929b42f5eab62cb1eb Author: Xℹ Ruoyao Date: Fri Jul 10 21:38:09 2020 +0800 libstdc++: use maintained size when split pb_ds binary search trees libstdc++-v3/ChangeLog:

[gcc r16-771] libstdc++: maintain subtree size in pb_ds binary search trees

https://gcc.gnu.org/g:2e27df6cbd05a3ee742434b7f50dbff5f363b487 commit r16-771-g2e27df6cbd05a3ee742434b7f50dbff5f363b487 Author: Xℹ Ruoyao Date: Fri Jul 10 20:58:04 2020 +0800 libstdc++: maintain subtree size in pb_ds binary search trees libstdc++-v3/ChangeLog: * i

[gcc r16-770] libstdc++: remove two redundant statements in pb_ds binary tree

https://gcc.gnu.org/g:6740732a659f9bef523f872c633d5477e8dc349c commit r16-770-g6740732a659f9bef523f872c633d5477e8dc349c Author: Xℹ Ruoyao Date: Fri Jul 10 20:10:52 2020 +0800 libstdc++: remove two redundant statements in pb_ds binary tree libstdc++-v3/ChangeLog: *