* src/Makefile.am (c_shadow_headers): Add features.h,
bits/wrap_features.h.
* src/Makefile.in: Regenerate.
* include/c_std/features.h: New file.
* include/c_std/bits/wrap_features.h (_CPP_WRAP_FEATURES_H): New
file. Need to have c++config.h included before this file so
_ISOC99_SOURCE around.
* include/c_std/sys/cdefs.h: Hack.
* include/c_std/stdlib.h: Same, use c++config.h.
* include/c_std/bits/std_cstdlib.h: Use _GLIBCPP_HAVE_STRTOLD.
* include/c_std/bits/std_cassert.h: Fix.
* include/c_std/bits/std_cerrno.h: Make consistent.
* include/c_std/bits/std_csetjmp.h (setjmp): Unscope global
declaration from ::_C_legacy to _C_legacy.
* include/c_std/bits/std_cstdio.h: same with printf.
* include/c_std/stdio.h: And here.
* include/c_std/bits/std_cstdlib.h: abort, exit comment.
* include/c_std/stdlib.h: Same here.