Only pass 6 arguments to the 'run' function on amd64.  amd64's
makecontext on FreeBSD only supports a maximum of 6 arguments.  This
fixes the setcontext_link test on amd64.

PR:		194828


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275033 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
MFamd64: Check for invalid flags in the machine context in sigreturn()
and setcontext().


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275035 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f