TurboJPEG: Fix 12-bit-per-sample arith-coded compr

(Regression introduced by 7bb958b732)

Because of 7bb958b732, the TurboJPEG
compression and encoding functions no longer transfer the value of
TJPARAM_OPTIMIZE into cinfo->data_precision unless the data precision
is 8.  The intent of that was to prevent using_std_huff_tables() from
being called more than once when reusing the same compressor object to
generate multiple 12-bit-per-sample JPEG images.  However, because
cinfo->optimize_coding is always set to TRUE by jpeg_set_defaults() if
the data precision is 12, calling applications that use 12-bit data
precision had to unset cinfo->optimize_coding if they set
cinfo->arith_code after calling jpeg_set_defaults().  Because of
7bb958b732, the TurboJPEG API stopped
doing that except with 8-bit data precision.  Thus, attempting to
generate a 12-bit-per-sample arithmetic-coded lossy JPEG image using
the TurboJPEG API failed with "Requested features are incompatible."

Since the compressor will always fail if cinfo->arith_code and
cinfo->optimize_coding are both set, and since cinfo->optimize_coding
has no relevance for arithmetic coding, the most robust and user-proof
solution is for jinit_c_master_control() to set cinfo->optimize_coding
to FALSE if cinfo->arith_code is TRUE.

This commit also:
- modifies TJBench so that it no longer reports that it is using
  optimized baseline entropy coding in modes where that setting
  is irrelevant,
- amends the cjpeg documentation to clarify that -optimize is implied
  when specifying -progressive or '-precision 12' without -arithmetic,
  and
- prevents jpeg_set_defaults() from uselessly checking the value of
  cinfo->arith_code immediately after it has been set to FALSE.

java/TJBench.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C)2009-2014, 2016-2019, 2021-2023 D. R. Commander.
+ * Copyright (C)2009-2014, 2016-2019, 2021-2024 D. R. Commander.
  *                                              All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -926,7 +926,6 @@ final class TJBench {
             System.out.println("Using fastest DCT/IDCT algorithm\n");
             fastDCT = true;
           } else if (argv[i].equalsIgnoreCase("-optimize")) {
-            System.out.println("Using optimized baseline entropy coding\n");
             optimize = true;
             xformOpt |= TJTransform.OPT_OPTIMIZE;
           } else if (argv[i].equalsIgnoreCase("-progressive")) {
@@ -1127,6 +1126,10 @@ final class TJBench {
         }
       }
 
+      if (optimize && !progressive && !arithmetic && !lossless &&
+          precision != 12)
+        System.out.println("Using optimized baseline entropy coding\n");
+
       if (precision == 16 && !lossless)
         throw new Exception("-lossless must be specified along with -precision 16");
       if (precision != 8 && doYUV)