Remove unused build_helper function

cmake_targets/tools/build_helper

@@ -733,43 +733,3 @@ set_openair_env(){
     export OPENAIR3_DIR=$openair_path/openair3
     export OPENAIR_TARGETS=$openair_path/targets
 }
-
-################################
-# Function to killall the subprocesses when Ctrl-C Key is hit
-###############################
-function handle_ctrl_c(){
-CURPID=$$
-ppid=$$
-arraycounter=1
-echo_info "** Trapped CTRL-C. Killing all subprocesses now..."
-echo_info "** Calling sync now..."
-sync
-while true
-do
-        FORLOOP=FALSE
-        # Get all the child process id
-        for i in `ps -ef| awk '$3 == '$ppid' { print $2 }'`
-        do
-                if [ $i -ne $CURPID ] ; then
-                        procid[$arraycounter]=$i
-                        arraycounter=`expr $arraycounter + 1`
-                        ppid=$i
-                        FORLOOP=TRUE
-                fi
-        done
-        if [ "$FORLOOP" = "FALSE" ] ; then
-           arraycounter=`expr $arraycounter - 1`
-           ## We want to kill child process id first and then parent id's
-           while [ $arraycounter -ne 0 ]
-           do
-             echo "first we send ctrl-c to program"
-             $SUDO kill -INT "${procid[$arraycounter]}"
-             sleep 5
-             echo "Now we force kill if that didn't work"
-             $SUDO kill -9 "${procid[$arraycounter]}" >/dev/null
-             arraycounter=`expr $arraycounter - 1`
-           done
-         exit
-        fi
-done
-}