[lltx] remark about new versions code

[Linas Stonys]

Hi,
I've compared versions:
*fontloader-2017-02-11.lua *
*fontloader-2018-10-28.lua *

and noticed a strange code about building /disccodes /table.
Previously it was build from /disccodes /and now from /glyphcodes/.

Old:
for i=0,#glyphcodes do
  glyphcodes[glyphcodes[i]]=i
end
for i=0,#*disccodes *do
*disccodes[disccodes[i]]*=i
end

New:
for k,v in next,glyphcodes do
  glyphcodes[v]=k
end
for k,v in next,*glyphcodes *do
*disccodes[v]*=k
end


Never mind if there is everything correct.

Linas