RFR(S) 8218751 Do not store original classfiles inside the CDS archive

[Ioi Lam]

http://cr.openjdk.java.net/~iklam/jdk13/8218751-dont-store-classfiles-in-cds.v01/
https://bugs.openjdk.java.net/browse/JDK-8218751

For JVMTI ClassFileLoadHook support, the CDS archive currently stores
the original classfile data of all archived classes.

However, this consists of over 30% of the archive size. Because all
original classfile data are already available in other files (such as the
JDK lib/modules file, or JAR files in the classpath), we can simply read
from these locations when needed by JVMTI.

For the default CDS archive (included as part of the JDK distribution),
the size is reduced from about 18.5MB to 12.1MB on Linux/x64.

Thanks

- Ioi