SemaTemplateInstantiateDecl.cpp: Suppress a warning. [-Wunused-variable]

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187765 91177308-0d34-0410-b5e6-96231b3b80d8
AST/DeclTemplate.h: Possibly fix a warning. [-Wuninitialized]

FIXME: Would '0' be an appropriate value in SequenceNumber?

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187766 91177308-0d34-0410-b5e6-96231b3b80d8