start switching decls over to using an allocator controlled by ASTContext.  
Right now only some ctors are switched over.  I need to switch them all
over so I can change the dtor over.

This lets us experiment with region allocation and other things in the 
future.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@48390 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed