Allow for locale in output of fc

In the Windows batch script this is already the case. Note that while
fc only produces two meaningful lines in the 'no diff' case, it does make
additional blank lines, so the clearest test is for the marker

    FC: No differences encountered

but allowing for language variation.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4783 de43f980-851b-0410-b2f7-c40aca1f87e0
Simplify checking for diff file changes

Both diff and fc return a non-zero errorlevel if there are differences, so
rather than need to check the nature of the files they produce, simply
check the errorlevel and use this to do a deletion if required.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4784 de43f980-851b-0410-b2f7-c40aca1f87e0