Apparently on hurd-i386 __GLIBC__ is defined, but the pthread
implementation is special and cannot be used with constexpr. Hence
exclude __gnu_hurd__.

Some Audio plugin (such as ALSA, and soon CoreAudio) already support microsecond level buffer time. However, current interval less than 1000 microseconds will cause a bug that the code treated as 0 ms.

Make sure this deprecated API is not used.

pthread_cond_timedwait() in PosixCond.hxx:timed_wait(PosixMutex...) returns
EINVAL, if ts.tv_nsec >= 1E9. In this case, it returns to early.

Find attached a patch which fixes this. I chose a compare-subtraction method
to keep ts.tv_nsec below 1E9.

Another option would be
ts.tv_sec += ts.tv_nsec / 1000000000;
ts.tv_nsec %= 1000000000;

But I guess this takes more time on some ARM processors, which don't support
hardware division.

Apparently all other C libraries are not compatible with "constexpr".
Those which are not will get a performance penalty, but at least they
work at all.

Apparently all other C libraries are not compatible with "constexpr".
Those which are not will get a performance penalty, but at least they
work at all.

On NetBSD, PTHREAD_MUTEX_INITIALIZER and PTHREAD_COND_INITIALIZER are
not compatible with C++11 "constexpr" (see Mantis ticket 0004110).  As
a workaround, don't ues "constexpr", and use the functions
pthread_mutex_init(), pthread_mutex_destroy(), pthread_cond_init() and
pthread_cond_destroy() instead.  This adds some runtime overhead, but
is portable to POSIX implementations that have awkward initializer
macros.

Bionic's pthread declarations are non-literal.

Use a custom pthread_mutex_t wrapper because std::mutex adds overhead.