Clean up tests.

Clean up tests.

On Windows with MSVC, just assume we have 64-bit file offset support,
including _fseeki64() and _ftelli64().

On UN*X, test for Large File Support and for fseeko()/ftello(), and for
what #defines are needed to enable them.

On Windows without MSVC, test for Large File Support, but assume we have
_fseeki64() and _ftelli64(); what *should* we be doing?

Clean up indentation and else()/endif() arguments while we're at it.

Change-Id: I801d1f4059abbed2d5123d2375a560634a9ee056
Reviewed-on: https://code.wireshark.org/review/28781
Petri-Dish: Guy Harris <guy@alum.mit.edu>
Tested-by: Petri Dish Buildbot
Reviewed-by: Guy Harris <guy@alum.mit.edu>