804b7cc438
This adds the integral overloads of std::to_chars and std::from_chars, including the changes made by P0682R0. Support for floating point types is absent. * include/Makefile.am: Add new <charconv> header. * include/Makefile.in: Regenerate. * include/precompiled/stdc++.h: Include <charconv>. * include/std/charconv: New file. (to_chars_result, to_chars, from_chars_result, from_chars): Define. * testsuite/20_util/from_chars/1.cc: New test. * testsuite/20_util/from_chars/1_neg.cc: New test. * testsuite/20_util/from_chars/2.cc: New test. * testsuite/20_util/from_chars/requirements.cc: New test. * testsuite/20_util/to_chars/1.cc: New test. * testsuite/20_util/to_chars/1_neg.cc: New test. * testsuite/20_util/to_chars/2.cc: New test. * testsuite/20_util/to_chars/requirements.cc: New test. From-SVN: r253353