libthread: rm FreeBSD 4 code

Pretty sure FreeBSD 4 is gone now. :-)

src/libthread/OpenBSD-386-asm.s

@@ -1 +1,52 @@
-#include "FreeBSD-386-asm.s"
+.globl _tas
+_tas:
+	movl $0xCAFEBABE, %eax
+	movl 4(%esp), %ecx
+	xchgl %eax, 0(%ecx)
+	ret
+
+.globl getmcontext
+getmcontext:
+	movl	4(%esp), %eax
+
+	movl	%fs, 8(%eax)
+	movl	%es, 12(%eax)
+	movl	%ds, 16(%eax)
+	movl	%ss, 76(%eax)
+	movl	%edi, 20(%eax)
+	movl	%esi, 24(%eax)
+	movl	%ebp, 28(%eax)
+	movl	%ebx, 36(%eax)
+	movl	%edx, 40(%eax)		 
+	movl	%ecx, 44(%eax)
+
+	movl	$1, 48(%eax)	/* %eax */
+	movl	(%esp), %ecx	/* %eip */
+	movl	%ecx, 60(%eax)
+	leal	4(%esp), %ecx	/* %esp */
+	movl	%ecx, 72(%eax)
+
+	movl	44(%eax), %ecx	/* restore %ecx */
+	movl	$0, %eax
+	ret
+
+.globl setmcontext
+setmcontext:
+	movl	4(%esp), %eax
+
+	movl	8(%eax), %fs
+	movl	12(%eax), %es
+	movl	16(%eax), %ds
+	movl	76(%eax), %ss
+	movl	20(%eax), %edi
+	movl	24(%eax), %esi
+	movl	28(%eax), %ebp
+	movl	36(%eax), %ebx
+	movl	40(%eax), %edx
+	movl	44(%eax), %ecx
+
+	movl	72(%eax), %esp
+	pushl	60(%eax)	/* new %eip */
+	movl	48(%eax), %eax
+	ret
+