Fully support OpenBSD 7.3

This change (1) upgrades to OpenBSD's newer kernel ABIs, and (2)
modifies APE to have a read-only data segment. Doing this required
creating APE Loader v1.1, which is backwards and forwards compatible
with the previous version.

If you've run the following commands in the past to install your APE
Loader systemwide, then you need to run them again. Ad-hoc installations
shouldn't be impacted. It's also recommended that APE binaries be remade
after upgrading, since they embed old versions of the APE Loader.

    ape/apeuninstall.sh
    ape/apeinstall.sh

This change does more than just fix OpenBSD. The new loader is smarter
and more reliable. We're now able create much tinier ELF and Mach-O data
structures than we could before. Both APE Loader and execvpe() will now
normalize ambiguous argv[0] resolution the same way as the UNIX shell.
Badness with TLS linkage has been solved.

Fixes #826

libc/crt/crt.S

@@ -22,6 +22,16 @@
 #include "libc/runtime/internal.h"
 .section .start,"ax",@progbits
 
+#if SupportsXnu() && defined(__x86_64__)
+//	XNU AMD64 Entrypoint
+//
+//	@note	Rosetta barely implements MAC_LC_UNIXTHREAD
+//	@note	Rosetta sets many registers to weird values
+_apple:	mov	$_HOSTXNU,%cl
+	jmp	1f
+	.endfn	_apple,weak,hidden
+#endif
+
 //	System Five userspace program entrypoint.
 //
 //	@param	rsp is [n,argv₀..argvₙ₋₁,0,envp₀..,0,auxv₀..,0,..]
@@ -32,18 +42,6 @@
 _start:
 #ifdef __x86_64__
 
-#if SupportsXnu()
-//	Hack for detecting M1 Rosetta environment.
-//	https://github.com/jart/cosmopolitan/issues/429#issuecomment-1166704377
-	cmp	$-1,%ebx
-	jne	0f
-	cmp	$+1,%edx
-	jne	0f
-	mov	$_HOSTXNU,%cl
-	xor	%edi,%edi
-0:
-#endif
-
 #if SupportsFreebsd()
 //	detect free besiyata dishmaya
 	test	%rdi,%rdi
@@ -54,7 +52,7 @@ _start:
 #endif
 
 //	set operating system when already detected
-	mov	%cl,__hostos(%rip)
+1:	mov	%cl,__hostos(%rip)
 
 //	get startup timestamp as early as possible
 //	its used by --strace flag and kprintf() %T