Reduce the number of symbols by changing how templates are instantiated per function bound in the registry.

Summary:
Reduce the number of symbols by changing how templates are instantiated per function bound in the registry.
This change reduces the number of sections in Registry.cpp.o by a little over 10%.

Reviewers: klimek

CC: cfe-commits, revane

Differential Revision: http://llvm-reviews.chandlerc.com/D1557

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189676 91177308-0d34-0410-b5e6-96231b3b80d8