SunOS version, but our shared libraries are not THAT much like SunOS.
In NetBSD a.out shared libraries, trampoline stubs have _DYNAMIC+n
as their symbol, so we can recognize them with strcmp. We may also
need SKIP_TRAMPOLINE_CODE(pc) eventually, but doing that right takes
machine dependent code to lookup what the _DYNAMIC stub jumps to.
(gdb appears to work OK on a.out without SKIP_TRAMPOLINE_CODE)