processctl() PCTL_SPAWN cmd, scheduler embryo state, redirected pipes

kernel/proc/proc.h

@@ -25,10 +25,10 @@ typedef struct {
 } ProcPlatformData;
 
 enum {
-  PROC_READY,
-  PROC_RUNNING,
-  PROC_ZOMBIE,
-  PROC_WAITING,
+  PROC_EMBRYO = 0,
+  PROC_READY = 1,
+  PROC_ZOMBIE = 2,
+  PROC_WAITING = 3,
 };
 
 typedef struct Proc {
@@ -46,6 +46,7 @@ typedef struct Proc {
   VfsObj *vobjs[PROC_VFSHANDLES_MAX];
   uint64_t vobjcnt;
   IpcPipe *pipes[PROC_PIPEHANDLES_MAX];
+  SpinLock pipes_spinlock;
   struct {
     IpcPipe *list;
     SpinLock spinlock;