swift234

[Global Opt] get ready to replace GlobalAddrInst with SILGlobalAddrInst.

We add two more fields to SILGlobalVariable: a VarDecl and a flag to see if this
is a declaration. VarDecl is mainly used for debugger support, it is also used
to check if the variable is weak imported.

We also modify the serializer to serialize the extra two fields.


Swift SVN r21883