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.
(*
* (c) 2011 Edouard Tisserant
*
* Fake semaphore support, for non preemptive implementation.
*
*)
FUNCTION_BLOCK SEMA
VAR_INPUT
CLAIM : BOOL;
RELEASE : BOOL;
END_VAR
VAR_OUTPUT
BUSY : BOOL;
END_VAR
VAR
Q_INTERNAL : BOOL;
END_VAR
Q_INTERNAL := CLAIM OR ( Q_INTERNAL AND (NOT RELEASE));
BUSY := Q_INTERNAL;
END_FUNCTION_BLOCK