Move e_pid and e_pgid to libprocess, Add get_self_pid () syscall

ce/ce.c

@@ -3,13 +3,14 @@
 #include "gapbuffer.h"
 #include "interp.h"
 #include "mprintf.h"
-#include "self.h"
 #include "strbuf.h"
 #include <arena.h>
+#include <debugconsole.h>
 #include <kb.h>
 #include <list.h>
 #include <malloc.h>
 #include <printf.h>
+#include <process_self.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -63,8 +64,7 @@ static void exec_line (const char* line) {
 }
 
 void app_main (void) {
-  e_pid = get_exec_pid ();
-  e_pgid = get_procgroup (e_pid);
+  libprocess_self_init ();
 
   struct edit_line edit_line;