* lib/linux/lseek.c (_lseek): New function.
* lib/linux/lseek.c (lseek): Use it to check if we should reset read
buffer.
* lib/mes/__buffered_read.c (__read_buffer_max): New variable.
(__buffered_read_init): Add environment override: MES_READ_BUFFER.
(__buffered_read): Use it.