Hi! Implement objtool support for the x86_64 stack swizzle pattern.
This means we can use the minial stack swizzle: mov %rsp, (%[tos]) mov %[tos], %rsp ... pop %rsp from inline asm, with arbitrary stack setup. The ORC data for the Top-of-Stack will use the SP_INDIRECT CFA base. In order for this to work, SP_INDIRECT needs to first dereference and then add the offset to find the next frame. Therefore we need to change SP_INDIRECT (which is currently unused) to mean: (%rsp) + offset. Changes since v1 include: - removed the !callee saved reg restriction by using the vals[] array over the regs[] array. - per the above, removed the patches creating the regs[] scratch space. - more comments. - rebased to tip/objtool/core
