Avoid collect2 calling signal unsafe functions and/or unlink with uninitialized memory

Avoid collect2 calling signal unsafe functions and/or unlink with uninitialized memory

2020-02-24  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* collect2.c (tool_cleanup): Avoid calling not signal-safe
	functions.
	(maybe_run_lto_and_relink): Avoid possible signal handler
	access to unintialzed memory (lto_o_files).