MFC r283506 (by rodrigc):

For objcopy, use --input-target and --output-target

When building with gcc 4.9 and binutils 2.25,
using '--input' and '--output' returns an error
message:
objcopy: option `--input' is ambiguous

MFC r283441:

Implement epoll family system calls. This is a tiny wrapper
around kqueue() to implement epoll subset of functionality.
The kqueue user data are 32bit on i386 which is not enough for
epoll user data, so we keep user data in the proc emuldata.

Initial patch developed by rdivacky@ in 2007, then extended
by Yuri Victorovich @ r255672 and finished by me
in collaboration with mjg@ and jillies@.

MFC r283424:

Add preliminary support for x86-64 Linux binaries.

Add preliminary support for x86-64 Linux binaries.

Differential Revision: https://reviews.freebsd.org/D1076