Add epoll and do more release readiness changes

This change also pays off some of the remaining technical debt with
stdio, file descriptors, and memory managemnt polyfills.

libc/stdio/g_stdout_init.S

@@ -33,10 +33,8 @@
 	ezlea	g_stdout_buf,cx
 	mov	%rcx,24(%rax)			#→ f.buf
 	movl	$BUFSIZ,32(%rax)		#→ f.size
-	ezlea	fwritebuf,cx
-	ezlea	fswritebuf,dx
-	testb	IsMetal()
-	cmovz	%rcx,%rdx
+	ezlea	__fwritebuf,cx
+	mov	%rcx,%rdx
 	mov	%rdx,48(%rax)			#→ f.writer
 	mov	%rax,stdout(%rip)
 	.init.end 400,_init_g_stdout,globl,hidden