Compile using flagfile so runs on Windows

As discussed in https://github.com/openlayers/ol3/issues/2100#issuecomment-51303801 a simple way to reduce the length of the command line is to use a flagfile. This PR uses the temp module in a similar way to the exports file. It could be changed to put all the compile options in a flagfile rather than just the js input sources.

As with #2591, needs someone with Windows to check that this fixes the problems.