Reset compressed size when combining JAR/ZIP archives

zlib does not always deflate a resource to the same compressed size as
the original input.  The input resource may have been compressed using
a different version of libz, or different compression settings.

Before adding each entry to the ZIP, clone the entry and reinitialize
the compressed field to -1 as is done by the more commonly used
ZipEntry(String) constructor.

This fixes a rare case where including a JAR in a java_binary() may
throw an error such as:

  invalid entry compressed size (expected 4271 but got 4275 bytes)