2.5.20 biuld fails because of lexer.cc

[Tim Hoffmann]

Hi,

I just tried to compile lilypond-2.5.20 on a debian testing system, but 
the build fails
because of lexer.cc. My system has flex 2.5.31-31 (wich is obviously > 
2.5.4a)
Here are the messages. Any Ideas?
(btw. building 2.5.14 worked a couple of weeks ago except for some 
problems in making
the info nodes...)

best
Tim

out/lexer.cc: In member function `virtual int Lily_lexer::yylex()':
out/lexer.cc:3331: error: `yy_current_buffer' undeclared (first use this
  function)
out/lexer.cc:3331: error: (Each undeclared identifier is reported only 
once for
  each function it appears in.)
lexer.ll:560: warning: unused variable `int cnv'
/usr/include/c++/3.3/bits/locale_facets.h: At top level:
out/lexer.cc:3208: warning: `int yy_start_stack_ptr' defined but not used
out/lexer.cc:3209: warning: `int yy_start_stack_depth' defined but not used
out/lexer.cc:3210: warning: `int*yy_start_stack' defined but not used
out/lexer.cc:3212: warning: `void yy_push_state(int)' declared `static' but
  never defined
out/lexer.cc:3215: warning: `void yy_pop_state()' declared `static' but 
never
  defined
out/lexer.cc:3218: warning: `int yy_top_state()' declared `static' but never
  defined
make[1]: *** [out/lexer.o] Error 1
make[1]: Leaving directory `/usr/local/src/lilypond-2.5.20/lily'
make: *** [all] Fehler 2


here are some lines from the ./config output as well
[...]
>checking gcc version... 3.3.4
[...]
>checking g++ version... 3.3.4
[...]
>checking for flex... flex
>checking how to run the C++ preprocessor... g++ -E
>checking FlexLexer.h usability... yes
>checking FlexLexer.h presence... yes
>checking for FlexLexer.h... yes
>checking for yyFlexLexer.yy_current_buffer... no