jlink should not be treated as a "small" tool

The linking of the JDK image using the jlink tool takes a considerable amount of time. However, the jlink tool is classified as a "small java" tool in the build script. This should only be used on quick small tools where a long startup time has a measurable performance impact. Clearly this does not apply to jlink.

The effect of removing the small tool flags are most pronounced when running a slowdebug build. Robbin Ehn, which made me aware of this, reduced the running time of jlink from 36 to 21 seconds on his machine by removing the "small" flags. On a release build, the effect is much less noticeable, but it's still worth fixing.