* lily/lexer.ll (avoid_silly_flex_induced_gcc_warnings): Disable.

* lily/lexer.ll (avoid_silly_flex_induced_gcc_warnings): Disable.

* lily/includable-lexer.cc [!HAVE_FLEXLEXER_YY_CURRENT_BUFFER]
(yy_current_buffer): New macro, compile hacks for flex 2.5.29.

* lily/include/includable-lexer.hh:
* lily/lexer.ll: Hack for multiple include of FlexLexer.h.

* config.hh.in (HAVE_FLEXLEXER_YY_CURRENT_BUFFER): Add.

* aclocal.m4: Regenerate.

* stepmake/aclocal.m4 (STEPMAKE_FLEXLEXER): Check for
yyFlexLexer.yy_current_buffer, which was removed in flex-2.5.29.