all: y2038 problem (hold until 2030)

[ghost]

I'm worried about time() returning long, while at my system long is 64 bit, it can be 32 bit at others.

Related issue: 0intro/9legacy#11

[rsc]

A significant amount of code uses long and should be vlong.
A significant amount of code uses ulong for unsigned 32-bit numbers and will need to be left alone (mostly corresponding to wire formats). That code will work until 2106.

I'm happy to start looking at this in 2030.

[ghost]

But they are unsigned 64 bit numbers at some systems (in my case amd64 glibc Linux), can that cause any conflicts right now?