This adds a push_target overload that takes a "target_ops_up &&".
This removes some calls to release a target_ops_up, and makes the
intent here clearer.
gdb/ChangeLog
2019-02-15 Tom Tromey <tromey@adacore.com>
* target.h (push_target): Declare new overload.
* target.c (push_target): New overload, taking an rvalue reference.
* remote.c (remote_target::open_1): Use push_target overload.
* corelow.c (core_target_open): Use push_target overload.