tests: use tput to get the number of columns

* tests/bison.in: here.

tests/bison.in

@@ -37,7 +37,7 @@ fi
 # We redirect stderr, which breaks the computation of the terminal
 # screen width.  So export COLUMNS to Bison, hoping for the shell to
 # have defined it.
-: ${COLUMNS=132}
+: ${COLUMNS=`tput cols || echo 132`}
 export COLUMNS
 $PREBISON "$abs_top_builddir/src/bison" ${1+"$@"} 2>"$stderr"
 status=$?