[BUG] Enhance SRT_ASSERT to print a log message

[maxsharabayko]

Release builds of SRT disable all the SRT_ASSERT assertions.
I might still be useful to print an error log message in that case.

#ifdef _DEBUG
#if defined(SRT_ENABLE_THREADCHECK)
#include "threadcheck.h"
#define SRT_ASSERT(cond, logger, msg) ASSERT(cond)
#else
#include <assert.h>
#define SRT_ASSERT(cond, logger, msg) assert(cond)
#endif
#else
#define SRT_ASSERT(cond, logger, msg) LOGC(logger.Error, log << "msg");
#endif

[ethouris]

You can use glog logger by default (using the full namespace path). This logger is almost not used, but this one is always turned on (that is, can't be blocked by FA selection).