Prompt dx/jack setting of command line in failure report.

Rationale:
The automated script that files divergences in buganizer
for our nightly fuzz tests did not include whether run
is with jack or with dx. This fixes that.

Test: nightly jfuzz
Change-Id: I7fca096e7b4758e35b8de8968e119e872d6793ab
diff --git a/tools/jfuzz/run_jfuzz_test.py b/tools/jfuzz/run_jfuzz_test.py
index 7e72aa1..58bc737 100755
--- a/tools/jfuzz/run_jfuzz_test.py
+++ b/tools/jfuzz/run_jfuzz_test.py
@@ -524,7 +524,9 @@
       jfuzz_args = ['\'-{0}\''.format(arg)
                     for arg in jfuzz_cmd_str.strip().split(' -')][1:]
       wrapped_args = ['--jfuzz_arg={0}'.format(opt) for opt in jfuzz_args]
-      repro_cmd_str = (os.path.basename(__file__) + ' --num_tests 1 ' +
+      repro_cmd_str = (os.path.basename(__file__) +
+                       ' --num_tests=1 ' +
+                       ('--use_dx ' if self._use_dx else '') +
                        ' '.join(wrapped_args))
       comment = 'jfuzz {0}\nReproduce test:\n{1}\nReproduce divergence:\n{2}\n'.format(
           jfuzz_ver, jfuzz_cmd_str, repro_cmd_str)