Fix global accessor and class linker errors.
Add global accessors to symbol list if VarDecl is fragile, i.e.
is non-resilient or its defining module allows non-resilient
access.
Don't set the class decl to hidden if it's in a package resilience
domain; even though its defining module is built resilently, the
class symbol should be visible across modules if they are in the
same package with resilience-bypass optimization. In such case,
treat its SubclassScope to Internal.
Resolves rdar://127321129
