DownloadURL last argument (targetFile) is now optional

Change-Id: I0864bcb052cddcc9753c056758b6e65fd561d928
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@qt.io>

coin/provisioning/common/unix/DownloadURL.sh

@@ -89,7 +89,14 @@ DownloadURL () {
     url=$1
     url2=$2
     expectedHash=$3
-    targetFile=$4
+    # Optional argument $4: destination filename
+    if [ x"$4" = x ]
+    then
+        # defaults to the last component of $url
+        targetFile=$(echo $url | sed 's|^.*/||')
+    else
+        targetFile=$4
+    fi
 
     if VerifyHash "$targetFile" "$expectedHash"
     then