golden hour

/usr/include/bits

File/Folder	Size	Actions
a.out.h	268 B
byteswap-16.h	1.69 KB
byteswap.h	5.56 KB
cmathcalls.h	4.7 KB
confname.h	23.19 KB
dirent.h	1.69 KB
dlfcn.h	2.47 KB
elfclass.h	426 B
endian.h	176 B
environments.h	3.5 KB
epoll.h	1.11 KB
errno.h	2.11 KB
error.h	2.62 KB
eventfd.h	1.1 KB
fcntl-linux.h	12.55 KB
fcntl.h	2.19 KB
fcntl2.h	5.44 KB
fenv.h	3.94 KB
fenvinline.h	190 B
huge_val.h	1.83 KB
huge_valf.h	1.79 KB
huge_vall.h	1.57 KB
hwcap.h	966 B
in.h	9.01 KB
inf.h	1.03 KB
initspin.h	25 B
inotify.h	1.05 KB
ioctl-types.h	2.41 KB
ioctls.h	4.38 KB
ipc.h	2.01 KB
ipctypes.h	1.14 KB
libc-lock.h	12.54 KB
libio-ldbl.h	1014 B
link.h	4.2 KB
local_lim.h	3.13 KB
locale.h	1.33 KB
math-finite.h	14.24 KB
mathcalls.h	11.3 KB
mathdef.h	2.14 KB
mathinline.h	30.86 KB
mman.h	4.78 KB
monetary-ldbl.h	1.02 KB
mqueue.h	1.22 KB
mqueue2.h	2.11 KB
msq.h	2.47 KB
nan.h	1.54 KB
netdb.h	1.25 KB
param.h	1.4 KB
poll.h	2.04 KB
poll2.h	2.86 KB
posix1_lim.h	4.81 KB
posix2_lim.h	2.82 KB
posix_opt.h	5.65 KB
printf-ldbl.h	986 B
pthreadtypes.h	6.33 KB
resource.h	9.21 KB
sched.h	7.37 KB
select.h	2.08 KB
select2.h	1.4 KB
sem.h	2.53 KB
semaphore.h	1.21 KB
setjmp.h	1.26 KB
setjmp2.h	1.67 KB
shm.h	3.44 KB
sigaction.h	2.79 KB
sigcontext.h	4.08 KB
siginfo.h	9.81 KB
signalfd.h	1.04 KB
signum.h	3.34 KB
sigset.h	4.48 KB
sigstack.h	1.49 KB
sigthread.h	1.64 KB
sockaddr.h	1.5 KB
socket.h	12.6 KB
socket2.h	2.95 KB
socket_type.h	2.16 KB
stab.def	8.82 KB
stat.h	7.46 KB
statfs.h	1.89 KB
statvfs.h	3.34 KB
stdio-ldbl.h	3.11 KB
stdio-lock.h	2.14 KB
stdio.h	5.45 KB
stdio2.h	12.36 KB
stdio_lim.h	1.34 KB
stdlib-float.h	1.12 KB
stdlib-ldbl.h	1.36 KB
stdlib.h	5.53 KB
string.h	56.48 KB
string2.h	46.08 KB
string3.h	4.38 KB
sys_errlist.h	1.19 KB
syscall.h	43.03 KB
sysctl.h	893 B
syslog-ldbl.h	1.17 KB
syslog-path.h	1.03 KB
syslog.h	1.66 KB
termios.h	5.23 KB
time.h	3.35 KB
timerfd.h	1.08 KB
timex.h	4.36 KB
types.h	7.55 KB
typesizes.h	3.15 KB
uio.h	2.42 KB
unistd.h	13.07 KB
ustat.h	1.06 KB
utmp.h	3.87 KB
utmpx.h	3.38 KB
utsname.h	1.19 KB
waitflags.h	1.61 KB
waitstatus.h	3.49 KB
wchar-ldbl.h	2.45 KB
wchar.h	1.11 KB
wchar2.h	20.04 KB
wordsize.h	327 B
xopen_lim.h	3.68 KB

Edit: environments.h

/* Copyright (C) 1999, 2001, 2004, 2009 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _UNISTD_H
# error "Never include this file directly.  Use <unistd.h> instead"
#endif

#include <bits/wordsize.h>

/* This header should define the following symbols under the described
   situations.  A value `1' means that the model is always supported,
   `-1' means it is never supported.  Undefined means it cannot be
   statically decided.

_POSIX_V7_ILP32_OFF32   32bit int, long, pointers, and off_t type
   _POSIX_V7_ILP32_OFFBIG  32bit int, long, and pointers and larger off_t type

_POSIX_V7_LP64_OFF32	   64bit long and pointers and 32bit off_t type
   _POSIX_V7_LPBIG_OFFBIG  64bit long and pointers and large off_t type

The macros _POSIX_V6_ILP32_OFF32, _POSIX_V6_ILP32_OFFBIG,
   _POSIX_V6_LP64_OFF32, _POSIX_V6_LPBIG_OFFBIG, _XBS5_ILP32_OFF32,
   _XBS5_ILP32_OFFBIG, _XBS5_LP64_OFF32, and _XBS5_LPBIG_OFFBIG were
   used in previous versions of the Unix standard and are available
   only for compatibility.
*/

#if __WORDSIZE == 64

/* Environments with 32-bit wide pointers are optionally provided.
   Therefore following macros aren't defined:
   # undef _POSIX_V7_ILP32_OFF32
   # undef _POSIX_V7_ILP32_OFFBIG
   # undef _POSIX_V6_ILP32_OFF32
   # undef _POSIX_V6_ILP32_OFFBIG
   # undef _XBS5_ILP32_OFF32
   # undef _XBS5_ILP32_OFFBIG
   and users need to check at runtime.  */

/* We also have no use (for now) for an environment with bigger pointers
   and offsets.  */
# define _POSIX_V7_LPBIG_OFFBIG	-1
# define _POSIX_V6_LPBIG_OFFBIG	-1
# define _XBS5_LPBIG_OFFBIG	-1

/* By default we have 64-bit wide `long int', pointers and `off_t'.  */
# define _POSIX_V7_LP64_OFF64	1
# define _POSIX_V6_LP64_OFF64	1
# define _XBS5_LP64_OFF64	1

#else /* __WORDSIZE == 32 */

/* By default we have 32-bit wide `int', `long int', pointers and `off_t'
   and all platforms support LFS.  */
# define _POSIX_V7_ILP32_OFF32	1
# define _POSIX_V7_ILP32_OFFBIG	1
# define _POSIX_V6_ILP32_OFF32	1
# define _POSIX_V6_ILP32_OFFBIG	1
# define _XBS5_ILP32_OFF32	1
# define _XBS5_ILP32_OFFBIG	1

/* We optionally provide an environment with the above size but an 64-bit
   side `off_t'.  Therefore we don't define _POSIX_V7_ILP32_OFFBIG.  */

/* Environments with 64-bit wide pointers can be provided,
   so these macros aren't defined:
   # undef _POSIX_V7_LP64_OFF64
   # undef _POSIX_V7_LPBIG_OFFBIG
   # undef _POSIX_V6_LP64_OFF64
   # undef _POSIX_V6_LPBIG_OFFBIG
   # undef _XBS5_LP64_OFF64
   # undef _XBS5_LPBIG_OFFBIG
   and sysconf tests for it at runtime.  */

#endif /* __WORDSIZE == 32 */

#define __ILP32_OFF32_CFLAGS	"-m32"
#define __ILP32_OFFBIG_CFLAGS	"-m32 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64"
#define __ILP32_OFF32_LDFLAGS	"-m32"
#define __ILP32_OFFBIG_LDFLAGS	"-m32"
#define __LP64_OFF64_CFLAGS	"-m64"
#define __LP64_OFF64_LDFLAGS	"-m64"