Fix reading of 16-bit TIFF images on big endian host.

Use correct integer types for arguments to TIFFGetField to avoid corruption
of values and failed loads of TIFF file when using cv::imread().

Added test where both big and little endian TIFF files are read using imread().

Fixed build of 3rdparty libtiff on big endian hosts.

Reduced memory required during decode_tile16384x16384 test by not converting
large grayscale test image to color image during read.

3rdparty/libtiff/tif_config.h.cmakein

@@ -54,7 +54,7 @@
 
 /* Native cpu byte order: 1 if big-endian (Motorola) or 0 if little-endian
    (Intel) */
-#define HOST_BIGENDIAN 0
+#define HOST_BIGENDIAN @HOST_BIGENDIAN@
 
 /* Set the native cpu bit order (FILLORDER_LSB2MSB or FILLORDER_MSB2LSB) */
 #define HOST_FILLORDER FILLORDER_LSB2MSB