detect absolute/relative paths in pkgfs

lib/pkgfs.lua

@@ -99,7 +99,9 @@ function pkgfs.component.close(handle)
 end
 
 function pkgfs.add(fname,comp)
- local fname = "/"..fnormalize(os.getenv("PWD").."/"..fname)
+ if fname:sub(1,1) ~= "/" then
+  fname = "/"..fnormalize(os.getenv("PWD").."/"..fname)
+ end
  local f = fopen(fname,comp)
  if not fname then error("unable to open file") end
  print(fname)