Please describe the problem:
Flex-2.5.34 gets confused:

libIDL 0.8.9 configuration complete

  C Preprocessor: "gcc -E"
  Standard input supported.

bison -y -d -v 2>/dev/null ./parser.y
touch stamp-parser
test -f y.tab.h && mv -f y.tab.h parser.h || touch parser.h
flex -8 -t ./lexer.l | sed -e 's/yy/__IDL_/g' >lexer.c
./lexer.l:116: bad character: %
./lexer.l:116: unknown error processing section 1
./lexer.l:116: unknown error processing section 1
./lexer.l:116: bad character: 5
./lexer.l:116: bad character: 0
./lexer.l:116: bad character: 0
./lexer.l:116: bad character: 0
test -f y.tab.c && mv -f y.tab.c parser.c || touch parser.c

 This has the unfortunate result that lexer.c does not contain anything from lexer.l. so the link fails with
/bin/sh ./libtool --mode=link gcc  -O2   -o tstidl  tstidl.o libIDL-2.la -lglib-2.0   
gcc -O2 -o .libs/tstidl tstidl.o  ./.libs/libIDL-2.so /usr/lib/libglib-2.0.so 
./.libs/libIDL-2.so: undefined reference to `__IDL_cur_token_line'
./.libs/libIDL-2.so: undefined reference to `__IDL_lex_cleanup'
./.libs/libIDL-2.so: undefined reference to `__IDL_prev_token_line'
./.libs/libIDL-2.so: undefined reference to `__IDL_lex'
./.libs/libIDL-2.so: undefined reference to `__IDL_in'
./.libs/libIDL-2.so: undefined reference to `__IDL_lex_init'
collect2: ld returned 1 exit status


Steps to reproduce:
1. Try to use flex-2.5.34 as your flex.
2. configure ; make
3. 


Actual results:
 As in the summary.

Expected results:
 A successful build would be nice ;-)

Does this happen every time?
 Yes.

Other information:
 Will attach a patch as soon as I've filed this.