Merge of Wu's GSOC 09 branch (src.20090525.r4372.wu)

Main changes:
- COW optimization for safecopy.
- safemap, a grant-based interface for sharing memory regions between processes.
- Integration with safemap and complete rework of DS, supporting new data types
  natively (labels, memory ranges, memory mapped ranges).
- For further information:
  http://wiki.minix3.org/en/SummerOfCode2009/MemoryGrants

Additional changes not included in the original Wu's branch:
- Fixed unhandled case in VM when using COW optimization for safecopy in case
  of a block that has already been shared as SMAP.
- Better interface and naming scheme for sys_saferevmap and ds_retrieve_map
  calls.
- Better input checking in syslib: check for page alignment when creating
  memory mapping grants.
- DS notifies subscribers when an entry is deleted.
- Documented the behavior of indirect grants in case of memory mapping.
- Test suite in /usr/src/test/safeperf|safecopy|safemap|ds/* reworked
  and extended.
- Minor fixes and general cleanup.
- TO-DO: Grant ids should be generated and managed the way endpoints are to make
sure grant slots are never misreused.

kernel/proto.h

@@ -89,6 +89,12 @@ _PROTOTYPE( void check_runqueues_f, (char *file, int line) );
 _PROTOTYPE( char *rtsflagstr, (int flags) );
 _PROTOTYPE( char *miscflagstr, (int flags) );
 
+/* system/do_safemap.c */
+_PROTOTYPE( int map_invoke_vm, (int req_type,
+		endpoint_t end_d, int seg_d, vir_bytes off_d,
+		endpoint_t end_s, int seg_s, vir_bytes off_s,
+		size_t size, int flag));
+
 /* system/do_safecopy.c */
 _PROTOTYPE( int verify_grant, (endpoint_t, endpoint_t, cp_grant_id_t, vir_bytes,
 	int, vir_bytes, vir_bytes *, endpoint_t *));