hg: jdk10/hs: 8185694: Replace SystemDictionaryShared::_java_platform_loader with SystemDictionary::is_platform_class_loader()

[calvin.cheung at oracle.com]

Changeset: 0ecfd6c951a6
Author:    ccheung
Date:      2017-10-10 14:38 -0700
URL:       http://hg.openjdk.java.net/jdk10/hs/rev/0ecfd6c951a6

8185694: Replace SystemDictionaryShared::_java_platform_loader with SystemDictionary::is_platform_class_loader()
Summary: added the creation of _java_platform_loader
Reviewed-by: iklam, coleenp, mchung, dholmes, jiangli

! src/hotspot/share/classfile/systemDictionary.cpp
! src/hotspot/share/classfile/systemDictionary.hpp
! src/hotspot/share/classfile/vmSymbols.hpp
! src/hotspot/share/runtime/thread.cpp