../src/block/block_write.c: In function '__wt_block_write_off':
../src/block/block_write.c:190:6: warning: conversion to 'long unsigned int' from 'int64_t' may change the sign of the result [-Wsign-conversion]
../src/block/block_write.c:190:29: warning: conversion to 'int64_t' from 'long unsigned int' may change the sign of the result [-Wsign-conversion]

refs #811