rb_dlsym2csym    637 ext/dl/dl.c      freefunc_t f = rb_dlsym2csym(sym);
rb_dlsym2csym    197 ext/dl/ptr.c       f = rb_dlsym2csym(sym);
rb_dlsym2csym    230 ext/dl/ptr.c       f = rb_dlsym2csym(sym);
rb_dlsym2csym    285 ext/dl/ptr.c     data->free = DLFREEFUNC(rb_dlsym2csym(val));