[8u] Fix SupplementalJapaneseEraTest.java for jdks with symlinked conf dir

Problem:
Similar to JDK-8309138, testcase jdk/test/java/util/Calendar/SupplementalJapaneseEraTest.java copy tested jdk into scratch dir to do testing on it. This however does not work correctly for builds, in which conf directory is symlinked (such as fedora/rhel packages), causing failures due to missing jdk binary in scratch dir.

Solution:
Symlinks are followed when copying tested jdk.