In gdb.trace/tfile.c:add_memory_block(), we store memory address in
long, and assign (extend) to long long.  It is not correct if the MSB of
address is 1, and signed extension will fill the upper 32-bit of long
long with 1, which is not what we want here.

This patch is to use unsigned type.  OK?

-- 
Yao (齐尧)