Prune include of DataLayout.h from include/clang/Basic/TargetInfo.h. NFC
Use a forward declaration of DataLayout instead of including
DataLayout.h in clangs TargetInfo.h. This reduces include
dependencies toward DataLayout.h (and other headers such as
DerivedTypes.h, Type.h that is included by DataLayout.h).
Needed to move implemantation of TargetInfo::resetDataLayout
from TargetInfo.h to TargetInfo.cpp.
Reviewed By: rnk
Subscribers: jvesely, nhaehnle, cfe-commits, llvm-commits
Differential Revision: https://reviews.llvm.org/D69262