Removed allocation of utcb shared pages by mm0 completely.

- Now libl4 has no references to utcb page or shmat etc.
- Pager does not deal with special case utcb page allocation.
  It instead allocates a shared page from shm memory pool.
- All tasks working to original standard.

Next:
- Add per-thread utcb allocation from the kernel
- Add larger register file for standard ipc
- Add long ipc (up to 1Kb)

tasks/libposix/include/posix/posix_init.h

@@ -0,0 +1,6 @@
+#ifndef __POSIX_INIT_H__
+#define __POSIX_INIT_H__
+
+void posix_init(void);
+
+#endif /* __POSIX_INIT_H__ */

tasks/libposix/include/posix/shpage.h

@@ -0,0 +1,45 @@
+/*
+ * A default shared page is used by every thread
+ * to pass large data for system calls.
+ *
+ * This file contains relevant shpage definitions.
+ */
+#ifndef __LIBPOSIX_SHPAGE_H__
+#define __LIBPOSIX_SHPAGE_H__
+
+#include <l4/macros.h>
+#include <l4lib/arch/syscalls.h>
+#include <l4lib/arch/syslib.h>
+#include <l4lib/ipcdefs.h>
+#include <l4lib/utcb.h>
+#include INC_GLUE(memory.h)
+
+extern void *shared_page;
+
+int shared_page_init(void);
+
+/*
+ * Arguments that are too large to fit in message registers are
+ * copied onto another area that is still on the utcb, and the servers
+ * map-in the task utcb and read those arguments from there.
+ */
+
+static inline int copy_to_shpage(void *arg, int offset, int size)
+{
+	if (offset + size > PAGE_SIZE)
+		return -1;
+
+	memcpy(shared_page + offset, arg, size);
+	return 0;
+}
+
+static inline int copy_from_shpage(void *buf, int offset, int size)
+{
+	if (offset + size > PAGE_SIZE)
+		return -1;
+
+	memcpy(buf, shared_page + offset, size);
+	return 0;
+}
+
+#endif /* __LIBPOSIX_SHPAGE_H__ */