Add x86_64-linux-gnu emulator

I wanted a tiny scriptable meltdown proof way to run userspace programs
and visualize how program execution impacts memory. It helps to explain
how things like Actually Portable Executable works. It can show you how
the GCC generated code is going about manipulating matrices and more. I
didn't feel fully comfortable with Qemu and Bochs because I'm not smart
enough to understand them. I wanted something like gVisor but with much
stronger levels of assurances. I wanted a single binary that'll run, on
all major operating systems with an embedded GPL barrier ZIP filesystem
that is tiny enough to transpile to JavaScript and run in browsers too.

https://justine.storage.googleapis.com/emulator625.mp4

libc/sysv/calls/__utimensat-sysv.s

@@ -0,0 +1,2 @@
+.include "o/libc/sysv/macros.inc"
+.scall __utimensat$sysv 0x00540223ffff0118 globl hidden

libc/sysv/calls/futimens-sysv.s

@@ -0,0 +1,2 @@
+.include "o/libc/sysv/macros.inc"
+.scall futimens$sysv 0x00550222ffffffff globl hidden

libc/sysv/calls/futimens.s

@@ -1,2 +0,0 @@
-.include "o/libc/sysv/macros.inc"
-.scall futimens 0x00550222ffffffff globl

libc/sysv/calls/futimes-sysv.s

@@ -0,0 +1,2 @@
+.include "o/libc/sysv/macros.inc"
+.scall futimes$sysv 0x004d00ce208bffff globl hidden

libc/sysv/calls/futimes.s

@@ -1,2 +0,0 @@
-.include "o/libc/sysv/macros.inc"
-.scall futimes 0x004d00ce208bffff globl

libc/sysv/calls/futimesat-sysv.s

@@ -0,0 +1,2 @@
+.include "o/libc/sysv/macros.inc"
+.scall futimesat$sysv 0xffff01eeffff0105 globl hidden

libc/sysv/calls/futimesat.s

@@ -1,2 +0,0 @@
-.include "o/libc/sysv/macros.inc"
-.scall futimesat 0xffff01eeffff0105 globl hidden

libc/sysv/calls/utimensat.s

@@ -1,2 +0,0 @@
-.include "o/libc/sysv/macros.inc"
-.scall utimensat 0x00540223ffff0118 globl hidden