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/tinymath/log1p.S

@@ -20,7 +20,12 @@
 #include "libc/macros.h"
 .source	__FILE__
 
-log1p:	push	%rbp
+/	Returns log(𝟷+𝑥).
+/
+/	@param	𝑥 is double scalar in low half of %xmm0
+/	@return	double scalar in low half of %xmm0
+tinymath_log1p:
+	push	%rbp
 	mov	%rsp,%rbp
 	.profilable
 	push	%rax
@@ -48,12 +53,11 @@ log1p:	push	%rbp
 	fstpl	(%rsp)
 	vmovsd	(%rsp),%xmm0
 	jmp	0b
-	.endfn	log1p,globl
+	.endfn	tinymath_log1p,globl
+	.alias	tinymath_log1p,log1p
 
-	.section .rodata.cst16,"aM",@progbits,16
-	.align	16
+	.rodata.cst16
 .LC16:	.long	205731576
 	.long	2515933592
 	.long	16381
 	.long	0
-	.previous