* Patch the build system to allow building with an external zlib
instead of using the included one. Since the included zlib symbols
would be visible also to other JNI code (e.g. translators used by the
SWT libs), this could cause problems where a newer version was
required (e.g. libpng used by the PNG translator).
* Verified ALT_JDK_IMPORT_PATH as needed to be set.