Update to OpenJDK 8u252 (April Critical Patch Update)

• JDK-8223898, CVE-2020-2754: Forward references to Nashorn
• JDK-8223904, CVE-2020-2755: Improve Nashorn matching
• JDK-8224541, CVE-2020-2756: Better mapping of serial ENUMs
• JDK-8224549, CVE-2020-2757: Less Blocking Array Queues
• JDK-8225603: Enhancement for big integers
• JDK-8227542: Manifest improved jar headers
• JDK-8231415, CVE-2020-2773: Better signatures in XML
• JDK-8233250: Better X11 rendering
• JDK-8233410: Better Build Scripting
• JDK-8234027: Better JCEKS key support
• JDK-8234408, CVE-2020-2781: Improve TLS session handling
• JDK-8234825, CVE-2020-2800: Better Headings for HTTP Servers
• JDK-8234841, CVE-2020-2803: Enhance buffering of byte buffers
• JDK-8235274, CVE-2020-2805: Enhance typing of methods
• JDK-8236201, CVE-2020-2830: Better Scanner conversions
• JDK-8238960: linux-i586 builds are inconsistent as the newly build jdk is not able to reserve enough space for object heap

Full release notes: https://bitly.com/oj8u252