RFR [9] 8153498: Update the PostVMInitHook mechanism to use an internal package in the base module

[Mandy Chung]

> On Apr 5, 2016, at 2:51 AM, Chris Hegarty <chris.hegarty at oracle.com> wrote:
> 
> sun.misc.PostVMInitHook::run is called by the VM once its initialization is
> complete, when jdk_version_info.post_vm_init_hook_enabled bit is true.
> Since sun.misc will be moved out of the base module, the VM should
> look for the PostVMInitHook in a more suitable place, say jdk.internal.vm.
> 
> http://cr.openjdk.java.net/~chegar/8153498/

Looks okay.

Minor nit: would it be better to rename the vmSymbol to match the package name: 
   vmSymbols::jdk_internal_vm_PostVMInitHook()

Mandy