fix HP-only mode

it was showing the bar intended as the warning that there's no HP
under the shield. but I tried it and that bar just makes it look like
there *is* a sliver of health, which there isn't. so it's better off
without that in either mode.

vacuum_gambit.p8

@@ -320,6 +320,7 @@ function drawgame()
 end
 
 powcols=split"170,154,153,148,68"
+shlcols = split"204,220,221"
 function drawhud()
  -- 112-and-right is hud zone
  rectfill(112, 0, 127, 127,0x56)
@@ -337,12 +338,16 @@ function drawhud()
 
  inset(120,66,125,125)
  -- 57 px vertically
- local mxs, mxh = primary_ship.maxshield, primary_ship.maxhp
- if mxs + mxh > 1 then
+ local mxs, cs, mxh, ch = primary_ship.maxshield, primary_ship.shield, primary_ship.maxhp, primary_ship.hp
+ if (mxs > 0) and (mxh > 1) then
   local split = 57 * (mxs / (mxs + mxh-1)) \ 1 + 66
   line(121, split, 124, split, 0xba)
-  vertmeter(121,67,124,split-1,primary_ship.shield, mxs,{204,220,221})
-  vertmeter(121,split+1,124,124,primary_ship.hp-1, mxh-1, hpcols)
+  vertmeter(121,67,124,split-1,cs, mxs,shlcols)
+  vertmeter(121,split+1,124,124,ch-1, mxh-1, hpcols)
+ elseif mxs > 0 then
+  vertmeter(121,67,124,124,cs,mxs,shlcols)
+ elseif mxh > 1 then
+  vertmeter(121,67,124,124,ch-1,mxh-1,hpcols)
  else
   print("!", 122, 94, 9)
   print("!", 121, 93, 8)