Fix internal error in do_relocate_sections when using plugins.

Fix internal error in do_relocate_sections when using plugins.

In a previous patch for PR 14675, to fix a problem with
the .eh_frame section when static linking, I added a step to
finalize the .eh_frame section at the end of the first link
pass. This patch caused PR 18152, where a plugin-claimed
object caused a non-claimed object's layout to be deferred
until replacement files were read. The call to
finalize_eh_frame_section() is happening before the layout of
the deferred objects, leading to the internal error in
do_relocate_sections.

This patch moves the finalization of the .eh_frame section to
after deferred objects have been processed.

gold/
	PR gold/14675
	PR gold/18152
	* gold.cc (queue_middle_tasks): Finalize .eh_frame after laying out
	deferred objects.