Add -nowrite arg to TJBench to improve consistency

Prevents any images from being written to disk, thus making the
performance of the benchmark as CPU-bound as possible.
diff --git a/ChangeLog.txt b/ChangeLog.txt
index 3279b46..16f695b 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -52,6 +52,11 @@
 JSIMD_FORCENONE environment variable to 1 (the other SIMD implementations
 already had this capability.)
 
+[11] Added a new command-line argument to TJBench (-nowrite) that prevents the
+benchmark from outputting any images.  This removes any potential operating
+system overhead that might be caused by lazy writes to disk and thus improves
+the consistency of the performance measurements.
+
 
 1.4.2
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