Fix illumos compile error in coreclr/vm/appdomain.hpp (#117462)

src/coreclr/vm/appdomain.hpp:1934:40: error: declaration of 'constexpr SystemDomain** const cdac_data<SystemDomain>::SystemDomain' changes meaning of 'SystemDomain' [-Wchanges-meaning]
   1934 |     static constexpr PTR_SystemDomain* SystemDomain = &SystemDomain::m_pSystemDomain;
        |                                        ^~~~~~~~~~~~
  src/coreclr/vm/appdomain.hpp:1934:56: note: used here to mean 'class SystemDomain'
   1934 |     static constexpr PTR_SystemDomain* SystemDomain = &SystemDomain::m_pSystemDomain;
        |                                                        ^~~~~~~~~~~~
  src/coreclr/vm/appdomain.hpp:1629:7: note: declared here
   1629 | class SystemDomain final
        |       ^~~~~~~~~~~~

Author: gwr

src/coreclr/debug/runtimeinfo/datadescriptor.h

@@ -927,7 +927,7 @@ CDAC_GLOBAL_STRING(RID, RID_STRING)
 CDAC_GLOBAL(GCInfoVersion, uint32, GCINFO_VERSION)
 
 CDAC_GLOBAL_POINTER(AppDomain, &AppDomain::m_pTheAppDomain)
-CDAC_GLOBAL_POINTER(SystemDomain, cdac_data<SystemDomain>::SystemDomain)
+CDAC_GLOBAL_POINTER(SystemDomain, cdac_data<SystemDomain>::SystemDomainPtr)
 CDAC_GLOBAL_POINTER(ThreadStore, &ThreadStore::s_pThreadStore)
 CDAC_GLOBAL_POINTER(FinalizerThread, &::g_pFinalizerThread)
 CDAC_GLOBAL_POINTER(GCThread, &::g_pSuspensionThread)

src/coreclr/vm/appdomain.hpp

@@ -1937,7 +1937,7 @@ inline static BOOL IsUnderDomainLock() { LIMITED_METHOD_CONTRACT; return m_Syste
 template<>
 struct cdac_data<SystemDomain>
 {
-    static constexpr PTR_SystemDomain* SystemDomain = &SystemDomain::m_pSystemDomain;
+    static constexpr PTR_SystemDomain* SystemDomainPtr = &SystemDomain::m_pSystemDomain;
 };
 #endif // DACCESS_COMPILE