# Check for 'make'
AC_CHECK_PROG(MAKE,make,yes,no)
if test "$MAKE" = no; then
    AC_MSG_ERROR(cannot compile - please install the 'make' utility.)
fi

# Check for 'm4'
AC_CHECK_PROG(M4,m4,yes,no)
if test "$M4" = no; then
    AC_MSG_ERROR(cannot compile - please install the 'm4' preprocessor.)
# Check for 'lex'
AC_CHECK_PROG(LEX,lex,yes,no)
if test "$LEX" = no; then
    AC_MSG_ERROR(cannot compile - please install the 'lex' lexical analyser.)
fi

# Make sure CFLAGS always works in the Makefile
if test -z "CFLAGS"; then
    CFLAGS="-g -O2"
fi