Use COUCH_BLOCK_SIZE instead of custom BLOCK_SIZE in couch_file_read.c
Use COUCH_BLOCK_SIZE instead of custom BLOCK_SIZE in couch_file_read.c

No effect on code (both constants have the same value).

Change-Id: Ibdd830f8138a56b41826ab3807fc07d0e6ee052a
Reviewed-on: http://review.couchbase.org/14701
Tested-by: Aaron Miller <41fcc51335f382e0855796cc35dd33f571f2d8f7@ninjawhale.com>
Reviewed-by: Aaron Miller <41fcc51335f382e0855796cc35dd33f571f2d8f7@ninjawhale.com>

abhinavdangeti/couchstore,jimwwalker/couchstore,couchbaselabs/couchstore-specials,hsharsha/couchstore,t3rm1n4l/couchstore,couchbaselabs/couchstore-specials,hsharsha/couchstore,jimwwalker/couchstore,hsharsha/couchstore,couchbaselabs/couchstore,couchbaselabs/couchstore-specials,vmx/couchstore,couchbaselabs/couchstore-specials,hsharsha/couchstore,couchbaselabs/couchstore,couchbaselabs/couchstore,vmx/couchstore,jimwwalker/couchstore,vmx/couchstore,t3rm1n4l/couchstore,abhinavdangeti/couchstore,couchbaselabs/couchstore-specials,abhinavdangeti/couchstore,t3rm1n4l/couchstore