[Development] Can't build docs anymore!

[Rohan McGovern]

Loaden said:
> I don't think this is a good idea, realy.
> We should find out a better way.
> 

Yes, that was only a workaround.

qtdoc/doc/doc.pri should be modified to avoid building such a huge
command.  As far as I know, it is valid to set an environment variable
in one make command and make use of it in the next, so I don't think
this needs to be built as a single huge command.

Maybe even the following patch is already enough, but I didn't test it:

  diff --git a/doc/doc.pri b/doc/doc.pri
  index c11b14d..fd41803 100644
  --- a/doc/doc.pri
  +++ b/doc/doc.pri
  @@ -18,7 +18,7 @@ $$unixstyle {
       SEP =
   } else {
       SET = set
  -    SEP = &&
  +    SEP = $$escape_expand(\\n\\t)
   }
   
   # The module names correspond to the names of files in qtbase/mkspecs/modules