AM_PROG_LEX sets this for some weird reason; it should
look for a program only and not a library. Then later
it gets linked to ar, ranlib, dlltool, windres, windmc
and itbl-test despite nothing in the code #include'ing
FlexLexer.h
This isn't a big deal but it did cause a build failure
on Cygwin as it triggered a bug with their flex package
dependencies which I reported at:
https://www.cygwin.com/ml/cygwin/2015-10/msg00433.html
Arguably I should remove all traces of LIBLEX in each
Makefile.am instead?
Signed-off-by: Ray Donnelly <mingw.android@gmail.com>
