finished 64 bit file offset support. Hopefully rsync can now transfer

finished 64 bit file offset support. Hopefully rsync can now transfer
files up to 2^64 bytes in size. Now I just need to find enough disk
space to test this :-)

The 64 bit offset code only works if off_t is 64 bits (or bigger!) on
both ends of the link. If one end tries to send a file greater than
2^31 in size and the other end doesn't support it then rsync will
abort.

This commit also cleans up some static declarations so they are in a
unitinitialised segment to save load time.