See http://sources.redhat.com/ml/gdb/2005-10/msg00118.html for the
motivation. Thanks to Daniel for the suggestion.

2005-10-20  Joel Brobecker  <brobecker@adacore.com>

        * Makefile.in (YYFILES): Add ada-lex.c

Tested on x86-linux by doing a "make -f src-release gdb.tar".
The resulting tarball contained the ada-lex.c file.

OK to commit?
-- 
Joel