Make it possible to suppress libTiff warning

The libTiff can produce a large amount of warning and it would be nice if there was a way suppress the warnings.

Example:

we are using QImageReader and Qimage to read TIFF Image files and observe a large number of warnings being printed to console, such as:

----------------------
TIFFReadDirectoryCheckOrder: Warning, Invalid TIFF directory; tags are not sorted in ascending order.
TIFFFetchNormalTag: Warning, ASCII value for tag "DocumentName" contains null byte in value; value incorrectly truncated during reading due to implementation limitations.
TIFFFetchNormalTag: Warning, ASCII value for tag "Artist" contains null byte in value; value incorrectly truncated during reading due to implementation limitations.
TIFFReadDirectoryCheckOrder: Warning, Invalid TIFF directory; tags are not sorted in ascending order.
TIFFFetchNormalTag: Warning, ASCII value for tag "DocumentName" contains null byte in value; value incorrectly truncated during reading due to implementation limitations.
TIFFFetchNormalTag: Warning, ASCII value for tag "Artist" contains null byte in value; value incorrectly truncated during reading due to implementation limitations.