[tlbuild] --enable-hitex trial

[Karl Berry]

Hi Johannes and all.

    2. run
      ctangle hiformat.w

I added an overkill of dependencies to try to make this happen (r61279),
namely:

$(hitex_OBJECTS): $(hiformat_c_h_l_y)
$(hishrink_OBJECTS): $(hiformat_c_h_l_y)

We'll see I guess.

    to extract hiformat.h (but at the same time overwrite SVN-tracked
    hilexer.l and hiparser.y, producing a 2630-lines diff).

Probably/hopefully none of those diffs are significant. Martin will
update them in svn eventually. It's a difficult situation. --thanks, karl.