The biggest change in this commit is to split the system classloader
into two: one for boot classes (e.g. java.lang.*) and another for
application classes. This is necessary to make OpenJDK's security
checks happy.
The rest of the changes include bugfixes and additional JVM method
implementations in classpath-openjdk.cpp.
Whereas the GNU Classpath port used the strategy of patching Classpath
with core classes from Avian so as to minimize changes to the VM, this
port uses the opposite strategy: abstract and isolate
classpath-specific features in the VM similar to how we abstract away
platform-specific features in system.h. This allows us to use an
unmodified copy of OpenJDK's class library, including its core classes
and augmented by a few VM-specific classes in the "avian" package.
See commit 8120bee4dc5f9ae2dec75a907778f1479ad398bd for the original
problem description and solution. That commit and a couple of related
ones had to be reverted when we found they had introduced GC-safety
regressions leading to crashes.
This commit restores the reverted code and fixes the regressions.
We're seeing race conditions which occasionally lead to assertion
failures and thus crashes, so I'm reverting these changes for now:
29309fb4149ec02f993f84ffe4675e95c98db832
e92674cb7337355dc4dd6317219010e5d1ce7e1c
8120bee4dc5f9ae2dec75a907778f1479ad398bd
