[binutils-gdb] Remove last reference to REMOTE_OBS

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT b8283aea9e599f17dbae7f52223994e3a9168143 ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: b8283aea9e599f17dbae7f52223994e3a9168143

Remove last reference to REMOTE_OBS

REMOTE_OBS was removed from Makefile.in in
18ca73470a0d7eb96a807c97559cbb9fddb4b461, but one reference remains.
This patch removes the lingerer.

ChangeLog
2018-05-27  Tom Tromey  <tom@tromey.com>

	* Makefile.in (DEPFILES): Don't reference REMOTE_OBS.