[mips] Print move instructions.

"move $4, $5" is printed instead of "or $4, $5, $zero".



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176455 91177308-0d34-0410-b5e6-96231b3b80d8
Check isDiscardableIfUnused, rather than hasLocalLinkage, when bumping
GlobalValue linkage up to ExternalLinkage in the ExtractGV pass. This
prevents linkonce and linkonce_odr symbols from being DCE'd.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176459 91177308-0d34-0410-b5e6-96231b3b80d8