[Driver] Replace Target with TargetInfo. Simplify LinkerInput.

This removes Target and moves the functionality it had over to TargetInfo.

This also simplifies LinkerInput by removing the InputKind. This will be handled elsewhere.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@174589 91177308-0d34-0410-b5e6-96231b3b80d8
[Driver] Add -L and -l support.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@174590 91177308-0d34-0410-b5e6-96231b3b80d8
[docs] lld self hosts.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@174592 91177308-0d34-0410-b5e6-96231b3b80d8
DynamicFile.
More prep for dynamic.
yep