Fix stack alignment and auxv for macho APE loader (#931)

ape/loader.c

@@ -947,6 +947,11 @@ EXTERN_C __attribute__((__noreturn__)) void ApeLoader(long di, long *sp,
     os = OPENBSD;
   }
 
+  /* xnu passes auxv as an array of strings */
+  if (os == XNU) {
+    *auxv = 0;
+  }
+
   /* detect netbsd and find end of words */
   pagesz = 0;
   for (ap = auxv; ap[0]; ap += 2) {

ape/start.S

@@ -23,6 +23,7 @@
 #ifdef __aarch64__
 
 _start:	mov	x1,sp
+	and     sp,x1,#-16
 	mov	x29,0
 	bl	ApeLoader
 	.endfn	_start,globl
@@ -33,6 +34,7 @@ XnuEntrypoint:
 	mov	$_HOSTXNU,%dl			// xnu's not unix!
 ElfEntrypoint:
 	mov	%rsp,%rsi			// save real stack
+	andq    $-16,%rsp                       // force SSE alignment
 	call	ApeLoader
 	.endfn	ElfEntrypoint,globl
 	.endfn	XnuEntrypoint,globl