range_tree: Provide more debug details upon unexpected add/remove

Sponsored-by: Klara, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Igor Ostapenko <igor.ostapenko@klarasystems.com>
Closes #17581

include/sys/metaslab_impl.h

@@ -539,6 +539,8 @@ typedef struct metaslab_unflushed_phys {
 	uint64_t	msp_unflushed_txg;
 } metaslab_unflushed_phys_t;
 
+char *metaslab_rt_name(metaslab_group_t *, metaslab_t *, const char *);
+
 #ifdef	__cplusplus
 }
 #endif