Fix build problem in fputs_maybe_filtered

Fix build problem in fputs_maybe_filtered

When merging commit 99f20f ("Fix style bug when paging") to master, I
had to make some changes to get it to compile again.  Unfortunately, I
must not have added these to the index at the correct time, because
they were not committed.

This patch fixes the problem.

gdb/ChangeLog
2019-05-08  Tom Tromey  <tromey@adacore.com>

	* utils.c (fputs_maybe_filtered): Call can_emit_style_escape as a
	method.