osd: Fixes for osd_scrub_during_recovery handling

osd: Fixes for osd_scrub_during_recovery handling

Fixes: http://tracker.ceph.com/issues/18206
Signed-off-by: David Zafman <dzafman@redhat.com>
(cherry picked from commit 367c32c69a512d2bea85a9b3860ec28bb4433750)

Conflicts:
	src/osd/OSD.cc (trivial)
	src/osd/PG.cc (trivial)
	src/test/osd/osd-recovery-scrub.sh (moved from qa/standalone/scrub/osd-recovery-scrub.sh)
		Fixes to osd-recovery_scrub.sh for Jewel compatibility
	src/osd/OSD.h (Jewel only - moved is_recovery_active() to OSDService)
	src/test/Makefile.am (Jewel only - add test to make check)
	src/test/osd/CMakeLists.txt (Jewel only - add test to make check)