JVMCI 0.48 released

[Doug Simon]

JVMCI 0.48 contains the following fix:

[GR-11357] Fix too strict No_Safepoint_Verifier (JDK-8209624)

The OracleJDK based binaries will soon be available at:

http://www.oracle.com/technetwork/oracle-labs/program-languages/downloads/index.html

The OpenJDK Linux and macOS binaries are at:

https://github.com/graalvm/openjdk8-jvmci-builder/releases/tag/jvmci-0.48

-Doug