time: prepare for 64-bit ints
time: prepare for 64-bit ints

The code was trying to interpret a uint32 n as a signed quantity
and then store it in an int. For this, int(n) currently works, but when
int becomes 64 bits one must write int(int32(n)) instead, to get
the 32-bit sign extension.

Update issue 2188.

R=golang-dev, nigeltao
CC=golang-dev
http://codereview.appspot.com/6551068

rflanagan/reginaldflanagan-project1,mhennings/marcohennings-go,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,mhennings/marcohennings-go,mhennings/marcohennings-go,scirelli/scirelli-go,bryanxu/go-zh,rdp/rogerpack2005-golang,rflanagan/reginaldflanagan-project1,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,scirelli/scirelli-go,sanjosh/sanjos100-tipc,d0f/go-zh,d0f/go-zh,webfd/go-zh,mhennings/marcohennings-go,scirelli/scirelli-go,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,rdp/rogerpack2005-golang,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,scirelli/scirelli-go,bryanxu/go-zh,mhennings/marcohennings-go,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,scirelli/scirelli-go,mhennings/marcohennings-go,rdp/rogerpack2005-golang,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,scirelli/scirelli-go,d0f/go-zh,mhennings/marcohennings-go,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,d0f/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,mhennings/marcohennings-go,bryanxu/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,d0f/go-zh,d0f/go-zh,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,scirelli/scirelli-go,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,d0f/go-zh,rdp/rogerpack2005-golang