[13] RFR (T/XS) 8223796: JVMCIEnv::get_jvmci_type does not keep klasses alive

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8223796/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8223796

The JVMCIEnv::get_jvmci_type() function has the block of code guarded by #ifdef INCLUDE_ALL_GCS and 
calls G1SATBCardTableModRefBS::enqueue() to keep Klass alive. However, the INCLUDE_ALL_GCS does not 
exist in jdk13 and the G1SATBCardTableModRefBS class does not exist either. We use the Access API to 
keep things alive.

Erik Österlund wrote:
"I think the klass handle looking thing (JVMCIKlassHandle) you get passed in already did 
klass_holder() and put that in a handle [1]. klass_holder() didn’t use to keep things alive but it 
does nowadays. Seems like removing the G1 stuff and the comment should be enough for jdk-jdk."

I removed this code as Erik suggested.

Thanks,
Vladimir

[1] 
http://hg.openjdk.java.net/jdk/jdk/file/f492567244ab/src/hotspot/share/jvmci/jvmciCompilerToVM.cpp#l50