Bug 26951: Fix execdesktop argument passing

Prior to this change, arguments with spaces were flattened, so running

    ./start-tor-browser.desktop --search "hello world"

would be converted to

    ./start-tor-browser.desktop --search hello world

opening up two windows, one search for "hello" and one trying to connect
to http://world

Fixes #18022 as well.

projects/tor-browser/RelativeLink/execdesktop

@@ -11,4 +11,4 @@ else
   echo "Launching '${TBB_START_PROG}'..."
 fi
 
-eval "${TBB_START_PROG} $@"
+${TBB_START_PROG} "$@"