SYSENTER/SYSCALL support

. add cpufeature detection of both
	. use it for both ipc and kernelcall traps, using a register
	  for call number
	. SYSENTER/SYSCALL does not save any context, therefore userland
	  has to save it
	. to accomodate multiple kernel entry/exit types, the entry
	  type is recorded in the process struct. hitherto all types
	  were interrupt (soft int, exception, hard int); now SYSENTER/SYSCALL
	  is new, with the difference that context is not fully restored
	  from proc struct when running the process again. this can't be
	  done as some information is missing.
	. complication: cases in which the kernel has to fully change
	  process context (i.e. sigreturn). in that case the exit type
	  is changed from SYSENTER/SYSEXIT to soft-int (i.e. iret) and
	  context is fully restored from the proc struct. this does mean
	  the PC and SP must change, as the sysenter/sysexit userland code
	  will otherwise try to restore its own context. this is true in the
	  sigreturn case.
	. override all usage by setting libc_ipc=1

servers/vm/main.c

@@ -294,6 +294,10 @@ void exec_bootproc(struct vmproc *vmp, struct boot_image *ip)
         if(sys_exec(vmp->vm_endpoint, (char *) execi->stack_high - 12,
 		(char *) ip->proc_name, execi->pc) != OK)
 		panic("vm: boot process exec of %d failed\n", vmp->vm_endpoint);
+
+	/* make it runnable */
+	if(sys_vmctl(vmp->vm_endpoint, VMCTL_BOOTINHIBIT_CLEAR, 0) != OK)
+		panic("VMCTL_BOOTINHIBIT_CLEAR failed");
 }
 
 void init_vm(void)
@@ -301,6 +305,7 @@ void init_vm(void)
 	int s, i;
 	static struct memory mem_chunks[NR_MEMS];
 	static struct boot_image *ip;
+	extern void __minix_init(void);
 
 #if SANITYCHECKS
 	incheck = nocheck = 0;
@@ -414,6 +419,11 @@ void init_vm(void)
 
 	/* Initialize the structures for queryexit */
 	init_query_exit();
+
+	/* Acquire kernel ipc vectors that weren't available
+	 * before VM had determined kernel mappings
+	 */
+	__minix_init();
 }
 
 /*===========================================================================*