[gcc r15-128] libstdc++: Update powerpc-linux-gnu baseline_symbols

https://gcc.gnu.org/g:212d93f4b3a2b63817b7b32efa1d910e5720ddc6 commit r15-128-g212d93f4b3a2b63817b7b32efa1d910e5720ddc6 Author: Andreas Schwab Date: Sat Feb 3 14:00:41 2024 +0100 libstdc++: Update powerpc-linux-gnu baseline_symbols *

[gcc r13-8610] libstdc++: Update baseline symbols for riscv64-linux

https://gcc.gnu.org/g:04128a403bd594dff50349e973b02b3f2d444d5d commit r13-8610-g04128a403bd594dff50349e973b02b3f2d444d5d Author: Andreas Schwab Date: Sun Dec 31 10:49:34 2023 +0100 libstdc++: Update baseline symbols for riscv64-linux *