tiff: Prefer enum TiffCompr over int for TiffContext.compr.

This is safer and helps debugging.
Signed-off-by: Diego Biurrun <diego@biurrun.de>

libavcodec/tiff.c

@@ -42,7 +42,7 @@ typedef struct TiffContext {
     int width, height;
     unsigned int bpp;
     int le;
-    int compr;
+    enum TiffCompr compr;
     int invert;
     int fax_opts;
     int predictor;