Added preliminary support for execve(). Updates to clone, fork, exit, task handling.

It turned out we used one version of kmalloc for malloc() and another for kfree()!
Now fixed.
Added parent-child relationship to tasks. Need to polish handling CLONE_PARENT and THREAD.

tasks/mm0/include/exit.h

@@ -0,0 +1,15 @@
+/*
+ * Definitions for do_exit() flags
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+
+#ifndef __EXIT_H__
+#define __EXIT_H__
+
+#define EXIT_THREAD_DESTROY		(1 << 0)
+#define EXIT_UNMAP_ALL_SPACE		(1 << 1)
+
+
+void do_exit(struct tcb *task, unsigned int flags, int status);
+#endif /* __EXIT_H__ */