#114 Asm/x{32,64}/7zCrcT8U.asm introduces executable stack

[Anthony G. Basile]

On PaX hardened kernels where executable stacks are not allowed --- the process gets killed --- p7zip will fail if the above asm is executed. This doesn't always happen, but it should be fixed in general. For further reference, see the gentoo bug

https://bugs.gentoo.org/show_bug.cgi?id=362337

A proposed patch is there.