Add check bison version in configure.ac file.
To build correctly matiec we need bison greater or equals than 2.4 version.
Now the "configure" script is able to check if system has correctly requirements.
include ../common.mk
AM_YFLAGS = -d
AM_LFLAGS = -o$(LEX_OUTPUT_ROOT).c
# Make sure this header file is generated first (by bison), as it is included
# by other C++ code that will also be compiled.
BUILT_SOURCES = iec_bison.h
CLEANFILES = \
iec_flex.cc \
iec_bison.cc \
iec_bison.h
lib_LIBRARIES = libstage1_2.a
libstage1_2_a_SOURCES = \
iec_flex.ll \
iec_bison.yy \
stage1_2.cc
libstage1_2_a_CPPFLAGS = -DDEFAULT_LIBDIR='"lib"' -I../../absyntax