* ldlang.c (lang_insert_orphan): Provide start/stop loadaddr syms
rather than defining unconditionally.
(lang_leave_overlay_section): Likewise.
* ld.texinfo (Overlay Description): Update description and examples
for start/stop syms.
ld/testsuite/
* ld-elf/overlay.d: -u symbols we want to see in the output.