vm: add third-party mmap() mode and PROCCTL

these two functions will be used to support all exec() functionality
going into a single library shared by RS and VFS and exec() knowledge
leaving VM.

	. third-party mmap: allow certain processes (VFS, RS) to
	  do mmap() on behalf of another process
	. PROCCTL: used to free and clear a process' address space

lib/libsys/Makefile

@@ -127,6 +127,7 @@ SRCS=  \
 	vm_push_sig.c \
 	vm_umap.c \
 	vm_yield_get_block.c \
+	vm_procctl.c \
 	vprintf.c \
 
 .if ${MKCOVERAGE} != "no"

lib/libsys/vm_procctl.c

@@ -0,0 +1,22 @@
+
+#include "syslib.h"
+
+#include <minix/vm.h>
+#include <string.h>
+
+/*===========================================================================*
+ *                                vm_exit				     *
+ *===========================================================================*/
+int vm_procctl(endpoint_t ep, int param)
+{
+    message m;
+    int result;
+
+    memset(&m, 0, sizeof(m));
+
+    m.VMPCTL_WHO = ep;
+    m.VMPCTL_PARAM = param;
+
+    result = _taskcall(VM_PROC_NR, VM_PROCCTL, &m);
+    return(result);
+}