Add segmented stack support for DragonFlyBSD.

Patch by Michael Neumann.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224936 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Remove unused classes from tablegen instruction info.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224937 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Refactor some tablegen instruction info classes slightly to prepare for another change. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224938 91177308-0d34-0410-b5e6-96231b3b80d8
[X86] Add the 0x82 instructions to the disassebmler. They are identical in functionality to the 0x80 opcode instructions, but are not valid in 64-bit mode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224939 91177308-0d34-0410-b5e6-96231b3b80d8
[X86] Fix some cases where some 8-bit instructions were marked as being convertible to three address instructions, but aren't really.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224940 91177308-0d34-0410-b5e6-96231b3b80d8