Always tweak EXIF w/h tags w/ lossless transforms

... even if using libjpeg v6b emulation.  Previously
adjust_exif_parameters() was only called with libjpeg v7/v8 emulation,
but due to a bug (which this commit also fixes), it only worked properly
with libjpeg v8 emulation.

ChangeLog.md

@@ -28,6 +28,16 @@ built with libjpeg v7 API/ABI emulation.  This was apparently a long-standing
 bug that has existed since the introduction of libjpeg v7/v8 API/ABI emulation
 in libjpeg-turbo v1.1.
 
+7. The lossless transform features in jpegtran and the TurboJPEG API will now
+always attempt to adjust the EXIF image width and height tags if the image size
+changed as a result of the transform.  This behavior has always existed when
+using libjpeg v8 API/ABI emulation.  It was supposed to be available with
+libjpeg v7 API/ABI emulation as well but did not work properly due to a bug.
+Furthermore, there was never any good reason not to enable it with libjpeg v6b
+API/ABI emulation, since the behavior is entirely internal.  Note that
+`-copy all` must be passed to jpegtran in order to transfer the EXIF tags from
+the source image to the destination image.
+
 
 1.5.1
 =====

transupp.c

@@ -1177,7 +1177,6 @@ transpose_critical_parameters (j_compress_ptr dstinfo)
  * We try to adjust the Tags ExifImageWidth and ExifImageHeight if possible.
  */
 
-#if JPEG_LIB_VERSION >= 70
 LOCAL(void)
 adjust_exif_parameters (JOCTET *data, unsigned int length,
                         JDIMENSION new_width, JDIMENSION new_height)
@@ -1327,7 +1326,6 @@ adjust_exif_parameters (JOCTET *data, unsigned int length,
     offset += 12;
   } while (--number_of_tags);
 }
-#endif
 
 
 /* Adjust output image parameters as needed.
@@ -1421,14 +1419,21 @@ jtransform_adjust_parameters (j_decompress_ptr srcinfo,
       GETJOCTET(srcinfo->marker_list->data[5]) == 0) {
     /* Suppress output of JFIF marker */
     dstinfo->write_JFIF_header = FALSE;
-#if JPEG_LIB_VERSION >= 70
     /* Adjust Exif image parameters */
+#if JPEG_LIB_VERSION >= 80
     if (dstinfo->jpeg_width != srcinfo->image_width ||
         dstinfo->jpeg_height != srcinfo->image_height)
       /* Align data segment to start of TIFF structure for parsing */
       adjust_exif_parameters(srcinfo->marker_list->data + 6,
         srcinfo->marker_list->data_length - 6,
         dstinfo->jpeg_width, dstinfo->jpeg_height);
+#else
+    if (dstinfo->image_width != srcinfo->image_width ||
+        dstinfo->image_height != srcinfo->image_height)
+      /* Align data segment to start of TIFF structure for parsing */
+      adjust_exif_parameters(srcinfo->marker_list->data + 6,
+        srcinfo->marker_list->data_length - 6,
+        dstinfo->image_width, dstinfo->image_height);
 #endif
   }