gdbserver: Use warning for warnings

gdb/gdbserver/ChangeLog:
2016-11-23  Pedro Alves  <palves@redhat.com>

	* event-loop.c (handle_file_event): Use warning.
	* linux-low.c (linux_resume_one_lwp_throw): Use warning.
	* mem-break.c (add_breakpoint_condition, add_breakpoint_commands):
	Use warning.
4 files changed