runtime: Fix __go_symbol_value val argument to backtrace_syminfo.

From-SVN: r192194

libgo/runtime/go-caller.c

@@ -144,7 +144,7 @@ __go_symbol_value (uintptr_t pc, uintptr_t *val)
 {
   *val = 0;
   backtrace_syminfo (__go_get_backtrace_state (), pc, syminfo_callback,
-		     error_callback, &val);
+		     error_callback, val);
   return *val != 0;
 }