Use makedoc generated texinfo documentation for reentrant syscalls
We use texinfo nodes beginning with an underscore in several other places, so
revert this ancient workaround for a no longer existing bug, and use the makedoc
generated texinfo for reentrant versions of syscalls, rather than handwritten
documentation.
Also alphabetically sort these functions.
Also add documentation for _execve_r, _getpid_r, _kill_r and _times_r functions,
whose non-reentrant versions are documented as stubs
v2:
Keep _open64_r, _lseek64_r and _fstat64_r functions under texinfo conditional STDIO64
Add _stat64_r function likewise.
Notes:
1. The handwritten prototypes give the reentrancy structure pointer as of type
void *, rather than the presumably more correct struct __reent *
2. The fcntl, gettimeofday, mkdir and rename functions are not documented as
stubs, so I haven't added the reentrant versions either
Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>