Stop resetting NoFramePointerElim in TargetMachine::resetTargetOptions.

Stop resetting NoFramePointerElim in TargetMachine::resetTargetOptions.

This is part of the work to remove TargetMachine::resetTargetOptions.

In this patch, instead of updating global variable NoFramePointerElim in
resetTargetOptions, its use in DisableFramePointerElim is replaced with a call
to TargetFrameLowering::noFramePointerElim. This function determines on a
per-function basis if frame pointer elimination should be disabled.

There is no change in functionality except that cl:opt option "disable-fp-elim"
can now override function attribute "no-frame-pointer-elim".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238080 91177308-0d34-0410-b5e6-96231b3b80d8