correct an off-by-one error

since our loop starts at i=1, we are not able to request a top matrix.
ie when requesting depth=1, the loop breaks on the first iteration -
always incorrectly returning the initialized identity matrix

src/librt/db_fullpath.cpp

@@ -863,7 +863,7 @@ db_path_to_mat(
     mat_t mtmp = MAT_INIT_IDN;
     for (size_t i = 1; i < pathp->fp_len; i++) {
 	mat_t cur_m = MAT_INIT_IDN;
-	if (depth && i + 1 > (size_t)depth)
+	if (depth && i > (size_t)depth)
 	    break;
 	struct directory *cdp = pathp->fp_names[i-1];
 	struct directory *dp = pathp->fp_names[i];