Adding a free address space cbs to the arena, initialising and finishing it, but not using it yet.

Moved CBSStruct to mpmst.h so that it can be included inline in ArenaStruct without circularity problems.

Copied from Perforce
 Change: 184044
 ServerID: perforce.ravenbrook.com

mps/code/cbs.h

@@ -10,7 +10,6 @@
 #define cbs_h
 
 #include "arg.h"
-#include "meter.h"
 #include "mpmtypes.h"
 #include "mpmst.h"
 #include "range.h"
@@ -21,21 +20,6 @@ typedef struct CBSStruct *CBS;
 typedef Bool (*CBSIterateMethod)(CBS cbs, Range range,
                                  void *closureP, Size closureS);
 
-
-#define CBSSig ((Sig)0x519CB599) /* SIGnature CBS */
-
-typedef struct CBSStruct {
-  SplayTreeStruct splayTree;
-  Count splayTreeSize;
-  MFSStruct blockPoolStruct;    /* FIXME: ref to why this is inlined */
-  Align alignment;
-  Bool fastFind;
-  Bool inCBS;                   /* prevent reentrance */
-  /* meters for sizes of search structures at each op */
-  METER_DECL(splaySearch);
-  Sig sig; /* sig at end because embeded */
-} CBSStruct;
-
 extern Bool CBSCheck(CBS cbs);
 
 extern Res CBSInit(Arena arena, CBS cbs, void *owner,