When bundling legal files, we need to filter them according to what 3rd
party components are actually included in the build. Several components,
such as zlib, libjpeg and freetype can be linked with system libraries
instead, and if so, we should also exclude the legal files for that
component.
This patch introduces a optional copy/filter step in the <module>-copy
targets. Since there are only two affected modules at this time I didn't
bother unifying this into one implementation. Instead the short logic is
duplicated between the two.
Bug: https://bugs.openjdk.java.net/browse/JDK-8199539
Webrev: http://cr.openjdk.java.net/~erikj/8199539/webrev.01/index.html
Bug: https://bugs.openjdk.java.net/browse/JDK-8199539
/Erik
