[yaml2obj] Add "-o" command line option to specify an output file name.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208900 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM64] Improve diagnostics for Cn operands in SYS instructions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208902 91177308-0d34-0410-b5e6-96231b3b80d8