Support for std::{from,to}_chars isn't finalized in
libcxx as of the time of writing, see __cpp_lib_to_chars in
6331bfa41a/libcxx/docs/FeatureTestMacroTable.rst
This patch adds a fallback using strtof. There are two
differences:
* strtof is locale-dependent
* strtof tolerates leading spaces
Signed-off-by: Mohamed Gaber <me@donn.website>
a5921d1ca9