RFR (S): 8204668: Cleanup management of the java.vm.info System property

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8204668
webrev: http://cr.openjdk.java.net/~dholmes/8204668/webrev/

JDK-8203329 fixed a problem where the native system property for the 
vm.info string was not updated after argument parsing, resulting in JVM 
TI reporting an incorrect value.

Looking at the overall approach for this property it can be simplified 
quite a bit. The basic issue is that it is initialized early in VM 
startup (so it can be present for crash logs) before argument parsing, 
but some details can change due to argument parsing. If we update the 
native value immediately after argument parsing, and so before the 
properties are passed through to the Java side, then we don't need to 
execute the Java code in reset_vm_info() to perform that update. 
Additionally, if we expose the SystemProperty directly (as done for 
other properties) then we can do away with the new 
PropertyList_update_value() function that has to search for the property 
to be updated.

Overall this cuts out a chunk of initialization code that may aid with 
startup costs; and simplifies the code.

There's some additional history in the bug report.

Testing:
   - tier 1, 2, 3
   - regression test from JDK-8203329:
      - 
serviceability/jvmti/GetSystemProperty/JvmtiGetSystemPropertyTest.java

Thanks,
David