Try to fix a windows warning.

Try to fix a windows warning.

win\lib\machine_id_win.cc(67): warning C4800: 'BOOL' : forcing value to bool 'true' or 'false' (performance warning)

BUG=none
TEST=none

[thakis, 2012-03-28 14:10:30]

I had tested http://code.google.com/p/rlz/source/detail?r=122 locally with msvc
2010 in both debug and release builds before committing, and the chromium commit
queue landed the roll from 121:122 without issues too.

But then the roll got reverted because it turned one builder red:
http://build.chromium.org/p/chromium/builders/Win%20Builder%202010%20%28dbg%2...
(r122 enabled warnings as errors).

Since I can't see this locally, this is a somewhat speculative fix.

[Roger Tawa (Google), 2012-03-28 15:57:57]

lgtm