4902. [test] Improved the reliability of the 'ixfr' system
test. [GL #66]
+4899. [test] Convert most of the remaining system tests to be able
+ to run in parallel, continuing the work from change
+ #4895. To take advantage of this, use "make -jN check",
+ where N is the number of processors to use. [GL #91]
+
4896. [test] cacheclean system test was not robust. [GL #82]
4895. [test] Allow some system tests to run in parallel.