Revert "Remove tests that test __gnu_lto_v1 symbol."

Revert "Remove tests that test __gnu_lto_v1 symbol."

Revert

commit 8c728a9d93e2342c57039fcdd6e4a502875b9e09
Author: Martin Liska <mliska@suse.cz>
Date:   Mon Jul 22 14:23:32 2019 +0200

    Remove tests that test __gnu_lto_v1 symbol.

since outputs of these tests are used by later tests.  Check the normal
symbol, foo, instead of __gnu_lto_v.*, which GCC stopped emitting after
r273662.

	* testsuite/ld-plugin/lto-3r.d: Restored.  Check foo instead
	of __gnu_lto_v.*.
	* testsuite/ld-plugin/lto-5r.d: Likewise.
	* testsuite/ld-plugin/lto.exp: Run lto-3r and lto-5r tests.