Bugfix: Replace bashisms with standard sh in tests/tools

qa/rpc-tests/send.sh

@@ -14,7 +14,7 @@ if [ $# -eq 0 ]; then
   exit 0
 fi
 
-if [ $1 == "-STOP" ]; then
+if [ $1 = "-STOP" ]; then
   if [ -s ${PIDFILE} ]; then
       kill -s ${SIGNAL} $(<${PIDFILE})
   fi

qa/rpc-tests/walletbackup.sh

@@ -149,7 +149,7 @@ echo "Creating transactions..."
 
 function S {
   TXID=$( $CLI -datadir=${D}/node${1} sendtoaddress ${2} "${3}" 0 )
-  if [[ $TXID == "" ]] ; then
+  if [ x$TXID = x ] ; then
       echoerr "node${1}: error sending ${3} btc"
       echo -n "node${1} balance: "
       $CLI -datadir=${D}/node${1} getbalance "*" 0