BUG: Windows BigTIFF errors: stat failure and lack of COMPRESSION_DEFLATE

Two bug fixes in itkTIFFImageIO.cxx:
1. On attempting to open a BigTIFF file 'stat' gave an error, because on Windows _stat64
must be used in this case.  The fix was to check for the OS, and if WIN32 use _stat64
in addition to stat.
2. The function TIFFReaderInternal::CanRead() was missing a line for COMPRESSION_DEFLATE.
This enables the formerally patented GIF compression, but the patent expired in 2006.

Change-Id: I6f1b0d95400c597f58a765e995e5e42b4bcd67ee
Merge topic 'WindowsBigTiff-release'

c4ded215 BUG: Windows BigTIFF errors: stat failure and lack of COMPRESSION_DEFLATE