dlsym
=====

POSIX specification:
 https://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html

Gnulib module: ---

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib:

  * This function is missing on some platforms: Minix 3.1.8, mingw, MSVC 14.

  * The visibility of symbols loaded in dependent shared libraries or present in the main executable is system dependent.