Validate privileged code relationships

- Work towards improving non-optimized build support
- Introduce MODE=zero which is -O0 without ASAN/UBSAN
- Use system GCC when ~/.cosmo.mk has USE_SYSTEM_TOOLCHAIN=1
- Have package.com check .privileged code doesn't call non-privileged

libc/nexgen32e/fentry.S

@@ -1,30 +0,0 @@
-/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
-│vi: set et ft=asm ts=8 tw=8 fenc=utf-8                                     :vi│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ Permission to use, copy, modify, and/or distribute this software for         │
-│ any purpose with or without fee is hereby granted, provided that the         │
-│ above copyright notice and this permission notice appear in all copies.      │
-│                                                                              │
-│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
-│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
-│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
-│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
-│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
-│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
-│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
-│ PERFORMANCE OF THIS SOFTWARE.                                                │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/macros.internal.h"
-.real
-.code16 # ∩ .code32 ∩ .code64
-
-//	Function entry hook stub.
-//
-//	@note	cc -pg -mfentry adds this to the start of every function
-//	@see	libc/log/shadowargs.ncabi.c
-//	@mode	long,legacy,real
-__fentry__:
-	ret
-	.endfn	__fentry__,weak

libc/nexgen32e/lolendian.S

@@ -1,77 +0,0 @@
-/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
-│vi: set et ft=asm ts=8 tw=8 fenc=utf-8                                     :vi│
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ Permission to use, copy, modify, and/or distribute this software for         │
-│ any purpose with or without fee is hereby granted, provided that the         │
-│ above copyright notice and this permission notice appear in all copies.      │
-│                                                                              │
-│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
-│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
-│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
-│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
-│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
-│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
-│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
-│ PERFORMANCE OF THIS SOFTWARE.                                                │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/macros.internal.h"
-
-//	@fileoverview Byte-order conversion functions.
-//
-//	Endianness is deceptively complicated to the uninitiated. Many
-//	helpers have been written by our top minds to address perceived
-//	difficulties. These ones got through standardization processes.
-//	To protect their legacy, all 19 functions have been implemented
-//	in just 17 bytes.
-//
-//	@see	READ32LE(), READ32BE(), etc.
-//	@asyncsignalsafe
-
-bswap_64:
-htobe64:
-htole64:
-be64toh:
-le64toh:mov	%rdi,%rax
-	bswap	%rax
-	ret
-	.endfn	le64toh,globl
-	.endfn	be64toh,globl
-	.endfn	htole64,globl
-	.endfn	htobe64,globl
-	.endfn	bswap_64,globl
-
-bswap_32:
-htobe32:
-htole32:
-be32toh:
-le32toh:
-ntohl:
-htonl:	mov	%edi,%eax
-	bswap	%eax
-	ret
-	.endfn	htonl,globl
-	.endfn	htole32,globl
-	.endfn	le32toh,globl
-	.endfn	be32toh,globl
-	.endfn	htobe32,globl
-	.endfn	ntohl,globl
-	.endfn	bswap_32,globl
-
-bswap_16:
-htobe16:
-htole16:
-be16toh:
-le16toh:
-ntohs:
-htons:	movzwl	%di,%eax
-	xchg	%al,%ah
-	ret
-	.endfn	htobe16,globl
-	.endfn	htons,globl
-	.endfn	le16toh,globl
-	.endfn	be16toh,globl
-	.endfn	htole16,globl
-	.endfn	ntohs,globl
-	.endfn	bswap_16,globl