[boost] [1.34.1, program_options] fix example/Jamfile.v2

From: Vladimir Prus (ghost_at_[hidden])
Date: 2007-07-06 13:24:26

It turns out that program_option's example/Jamfile.v2 
got stale, and does not work in 1.34.0, at all.

The attached patch fixes that, OK for 1.34.1?

- Volodya