This should have been done before the GCC 10.1 release.

libstdc++-v3/ChangeLog:

	* config/abi/post/powerpc-linux-gnu/baseline_symbols.txt:
	Update.
	* config/abi/post/powerpc64-linux-gnu/32/baseline_symbols.txt:
	Update.

Tested powerpc64-linux. Committed to trunk. Backport to gcc-10 to
follow.