Don't exclude amd64 from COMPAT < 15. We need it for COMPAT_NETBSD32 a.out
Move the empty sigreturn functions to their own files to allow the compat
module to load by itself.
PR/49287: Masao Uebayashi: Handle exec_script argument vector from the 32 ->
64 bit case. When execing a 64 bit shell from a 32 bit binary the argument
vector was still incorrect.

XXX: Pullup 7
add the two new compat files.
avoid local variable shadowing devname.
fix possibly uninitialized variable.
add a new "fo_mmap" fileops method to allow use of arbitrary uvm_objects for
mappings of file objects.  move vnode-specific details of mmap()ing a vnode
from uvm_mmap() to the new vnode-specific vn_mmap().  add new uvm_mmap_dev()
and uvm_mmap_anon() convenience functions for mapping character devices
and anonymous memory, and replace all other calls to uvm_mmap() with those.
use the new fileop in drm2 so that libdrm can use mmap() to map things
like on other platforms (instead of the ioctl that we have used so far).
fix powerpc TLS problems by removing the hacks for PPC EABI.
the kernel no longer treats R2 specially and its use as
the TLS register is now handled entirely in userland.
remove ep_name, change the last reference to use ep_kname instead.
welcome to 7.99.3.