fixes #116 Remove the 25% padding from toku_mempool_construct. Clean up

the bndata code that calls toku_mempool_construct.

ft/bndata.cc

@@ -114,8 +114,8 @@ void bn_data::initialize_from_data(uint32_t num_entries, unsigned char *buf, uin
     }
     KLPAIR *XMALLOC_N(num_entries, array); // create array of pointers to leafentries
     unsigned char *newmem = NULL;
-    // add same wiggle room that toku_mempool_construct would, 25% extra
-    uint32_t allocated_bytes = data_size + data_size/4;
+    // add 25% extra wiggle room
+    uint32_t allocated_bytes = data_size + (data_size / 4);
     CAST_FROM_VOIDP(newmem, toku_xmalloc(allocated_bytes)); 
     unsigned char* curr_src_pos = buf;
     unsigned char* curr_dest_pos = newmem;

util/mempool.cc

@@ -130,15 +130,13 @@ void toku_mempool_init(struct mempool *mp, void *base, size_t free_offset, size_
  */
 void toku_mempool_construct(struct mempool *mp, size_t data_size) {
     if (data_size) {
-        size_t mpsize = data_size + (data_size/4);     // allow 1/4 room for expansion (would be wasted if read-only)
-        mp->base = toku_xmalloc(mpsize);               // allocate buffer for mempool
-        mp->size = mpsize;
-        mp->free_offset = 0;                     // address of first available memory for new data
-        mp->frag_size = 0;                       // all allocated space is now in use
+        mp->base = toku_xmalloc(data_size);
+        mp->size = data_size;
+        mp->free_offset = 0;
+        mp->frag_size = 0;
     }
     else {
         toku_mempool_zero(mp);
-        //        fprintf(stderr, "Empty mempool created (base constructor)\n");
     }
 }