Added a counter of the total number of existing objects

It may simplify the control of the garbage collector.

lstate.h

@@ -250,6 +250,7 @@ typedef struct global_State {
   lua_Alloc frealloc;  /* function to reallocate memory */
   void *ud;         /* auxiliary data to 'frealloc' */
   l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
+  l_mem totalobjs;  /* total number of objects allocated */
   l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
   lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
   lu_mem lastatomic;  /* see function 'genstep' in file 'lgc.c' */