build failure

[Clint Adams]

With bogofilter-0.9.2.cvs+locking, I get

libbogofilter.a(lexer_head.o)(.text+0x1218): In function `yy_fatal_error': ITIMER_PROF/lexer_head.c:1869: undefined reference to `EXIT'
libbogofilter.a(lexer_text_plain.o)(.text+0x1018): In function `yy_fatal_error': ITIMER_PROF/lexer_text_plain.c:1515: undefined reference to `EXIT'
libbogofilter.a(lexer_text_html.o)(.text+0x1100): In function `yy_fatal_error': ITIMER_PROF/lexer_text_html.c:1539: undefined reference to `EXIT'