Remove code for the obsolete RLE image format

libjpeg-turbo never included that code, because it requires an external
library (the Utah Raster Toolkit.)  The RLE image format was supplanted
by GIF in the late 1980s, so it is rarely seen these days.  (It had a
lousy Weissman score, anyhow.)

cjpeg.c

@@ -69,9 +69,9 @@ static const char * const cdjpeg_message_table[] = {
  *     2) assume we can push back more than one character (works in
  *        some C implementations, but unportable);
  *     3) provide our own buffering (breaks input readers that want to use
- *        stdio directly, such as the RLE library);
+ *        stdio directly);
  * or  4) don't put back the data, and modify the input_init methods to assume
- *        they start reading after the start of file (also breaks RLE library).
+ *        they start reading after the start of file.
  * #1 is attractive for MS-DOS but is untenable on Unix.
  *
  * The most portable solution for file types that can't be identified by their
@@ -117,10 +117,6 @@ select_file_type(j_compress_ptr cinfo, FILE *infile)
   case 'P':
     return jinit_read_ppm(cinfo);
 #endif
-#ifdef RLE_SUPPORTED
-  case 'R':
-    return jinit_read_rle(cinfo);
-#endif
 #ifdef TARGA_SUPPORTED
   case 0x00:
     return jinit_read_targa(cinfo);