Build failure on macOS

[masaori335]

../include/tscpp/util/TsSharedMutex.h:62:14: error: incompatible integer to pointer conversion assigning to 'const char *' from 'int'
    _c_str = strerror_r(err_num, _buf, 256);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It looks like macOS has POSIX version strerror_r only.

STRERROR(3)                                                Library Functions Manual                                                STRERROR(3)

NAME
     perror, strerror, strerror_r, sys_errlist, sys_nerr – system error messages

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
...
     int
     strerror_r(int errnum, char *strerrbuf, size_t buflen);
...
STANDARDS
     The perror() and strerror() functions conform to ISO/IEC 9899:1999 (“ISO C99”).  The strerror_r() function conforms to IEEE Std
     1003.1-2001 (“POSIX.1”).