Turning pool init methods the right way in, so that they each call the next method up the class hierarchy.

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 Change: 190858
 ServerID: perforce.ravenbrook.com

mps/code/mpmst.h

@@ -81,7 +81,6 @@ typedef struct mps_pool_class_s {
   PoolDebugMixinMethod debugMixin; /* find the debug mixin, if any */
   PoolSizeMethod totalSize;     /* total memory allocated from arena */
   PoolSizeMethod freeSize;      /* free memory (unused by client program) */
-  Bool labelled;                /* whether it has been EventLabelled */
   Sig sig;                      /* .class.end-sig */
 } PoolClassStruct;