dso__next_symbol
sym = dso__next_symbol(sym);
sym = dso__next_symbol(sym);
for (sym = start; sym; sym = dso__next_symbol(sym)) {
for (sym = start; sym; sym = dso__next_symbol(sym)) {
for (; sym; sym = dso__next_symbol(sym)) {
struct symbol *dso__next_symbol(struct symbol *sym);