calls to zip_get() in file share/java/util/zip.c are potentially thread unsafe

It looks like calls to zip_get() are not thread-safe in jdk115 and jdk116g.

When loading classes, there is already a higher level lock around class loading so that only one thread can be loading classes at a time. Unfortunately, the system resource code in share/java/lang/resource.c was not written with this
in mind so that all of its calls to zip_get() are potentially unsafe.