* libc/include/sys/lock.h: Replaced empty {} with (0) to conform
with locking API.
* libc/include/sys/stdio.h: (_flockfile)[!_SINGLE_THREAD]: Add
check for__SSTR in _flags and if set, skip lock request.
(_funlockfile)[!SINGLE_THREAD]: Ditto.
* libc/stdio/local.h (CHECK_INIT): Added check that _REENT is
not NULL.
* libc/stdio/siprintf.c (siprintf, _siprintf_r): Added missing
initialisation of _file to -1 in local FILE.
* libc/stdio/snprintf.c (snprintf, _snprintf_r): Ditto.
* libc/stdio/sscanf.c (sscanf, _sscanf_r): Ditto.
* libc/stdio/vsnprintf.c (vsnprintf, _vsnprintf_r): Ditto.
* libc/stdio/vsscanf.c (_vsscanf_r): Ditto.
* libc/stdio/sscanf.c (sscanf, _sscanf_r): Added __SSTR flag to
_flags in local FILE to prevent locking.
* libc/stdio/vsscanf.c (_vsscanf_r): Ditto.
* libc/include/sys/_types.h (_flock_t): Added.
* libc/include/sys/lock.h (__lock_try_acquire): New interface.
(__lock_try_acquire_recursive): Ditto.
* libc/include/sys/reent.h (__sFILE, __sFILE64): Add new
_lock field.
* libc/stdio/findfp.c (std)[!__SINGLE_THREAD__]: Initialize _lock
field.
* libc/stdio/fopen.c (_fopen_r)[!__SINGLE_THREAD__]: Ditto.
* libc/stdio64/fopen64.c (_fopen64_r)[!__SINGLE_THREAD__]: Ditto.
* libc/sys/linux/include/time.h (struct timespec): Moved from
<sys/types.h> and added check for __need_timespec flag so type
can be defined by itself.
* libc/sys/linux/sys/_types.h (_flock_t): New type.
* libc/sys/linux/sys/types.h (struct timespec): Moved to
<time.h>.