[libc++] Follow-up to "Poison Pills are Too Toxic"

libcxx/docs/FeatureTestMacroTable.rst

libcxx/docs/ReleaseNotes/19.rst

libcxx/docs/Status/Cxx23.rst

libcxx/docs/Status/Cxx23Papers.csv

libcxx/include/version

...support.limits.general/algorithm.version.compile.pass.cpp

...upport.limits.general/functional.version.compile.pass.cpp

.../support.limits.general/iterator.version.compile.pass.cpp

...ts/support.limits.general/memory.version.compile.pass.cpp

...ts/support.limits.general/ranges.version.compile.pass.cpp

...s/support.limits.general/version.version.compile.pass.cpp

libcxx/utils/generate_feature_test_macro_components.py