1. [SelectionDAG] Make fast and linearize visible by clang -pre-RA-sched (details)
Commit 976a3e5f61415e784c85b341180eac300cc8b7a5 by
[SelectionDAG] Make fast and linearize visible by clang -pre-RA-sched

ScheduleDAGFast.cpp is compiled to object file, but the ScheduleDAGFast
object file isn't linked into clang executable file as no symbol is
referred by outside. Add calling to createXxx of ScheduleDAGFast.cpp,
then the ScheduleDAGFast object file will be linked into clang
executable file. The static RegisterScheduler will register scheduler
fast and linearize at clang boot time.

Reviewed By: pengfei

Differential Revision:
The file was modifiedllvm/include/llvm/CodeGen/TargetLowering.h
The file was addedclang/test/CodeGen/pre-ra-sched.c
The file was modifiedllvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp