Add quick hack for "no sample pressure but tank index changed" case

This isn't right if you switch back to the same cylinder multiple times,
but for the first time it kind of works - just take the beginning
cylinder pressure if we have one.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

profile.c

@@ -719,6 +719,8 @@ static struct plot_info *create_plot_info(struct dive *dive)
 		entry->same_cylinder = sample->cylinderindex == cylinderindex;
 		cylinderindex = sample->cylinderindex;
 		entry->pressure = sample->cylinderpressure.mbar;
+		if (!entry->same_cylinder && !entry->pressure)
+			entry->pressure = dive->cylinder[cylinderindex].start.mbar;
 		entry->temperature = sample->temperature.mkelvin;
 
 		if (depth || lastdepth)