Relax witness assertions related to prof_gdump().

In some cases the prof machinery allocates (in order to modify the
bt2gctx hash table), and such operations are synchronized via
bt2gctx_mtx.  Rather than asserting that no locks are held on entry
into functions that may call prof_gdump(), make the weaker assertion
that no "core" locks are held.  The prof machinery enqueues dumps
triggered by prof_gdump() calls when bt2gctx_mtx is held, so this
weakened assertion avoids false failures in such cases.

include/jemalloc/internal/witness.h

@@ -25,6 +25,14 @@ typedef int witness_comp_t (const witness_t *, const witness_t *);
 #define	WITNESS_RANK_PROF_TDATA		7U
 #define	WITNESS_RANK_PROF_GCTX		8U
 
+/*
+ * Used as an argument to witness_assert_depth_to_rank() in order to validate
+ * depth excluding non-core locks with lower ranks.  Since the rank argument to
+ * witness_assert_depth_to_rank() is inclusive rather than exclusive, this
+ * definition can have the same value as the minimally ranked core lock.
+ */
+#define WITNESS_RANK_CORE		9U
+
 #define	WITNESS_RANK_ARENA		9U
 #define	WITNESS_RANK_ARENA_CHUNKS	10U
 #define	WITNESS_RANK_ARENA_NODE_CACHE	11U