This introduces a variadic template and some helper macros to
safely and correctly deserialize many types of common record
fields while maintaining error checking.
Differential Revision: http://reviews.llvm.org/D20183
Reviewed By: rnk, amccarth
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269315 91177308-0d34-0410-b5e6-96231b3b80d8
