get_program_var_addr
static const void **get_program_var_addr(const char *, RtldLockState *);
get_program_var_addr("__libc_atexit", lockstate);
*get_program_var_addr("environ", &lockstate));
if ((addr = get_program_var_addr(name, NULL)) != NULL) {
uintptr_t)get_program_var_addr("__pthread_map_stacks_exec",