Add Dependency to Fix Parallel make test Runs

When run with `-jN`, the `rm tmp*` can run in the middle of the `test-lz4-dict`
job, which will then fail, finding its files to have been axed. This adds a
dependency between the two.

tests/Makefile

@@ -327,7 +327,7 @@ test-lz4-opt-parser: lz4 datagen
 
 test-lz4-essentials : lz4 datagen test-lz4-basic test-lz4-multiple \
                       test-lz4-frame-concatenation test-lz4-testmode \
-                      test-lz4-contentSize
+                      test-lz4-contentSize test-lz4-dict
 	@$(RM) tmp*
 
 test-lz4: lz4 datagen test-lz4-essentials test-lz4-opt-parser \