Since I was feeling bad for the Windows 7 build slave not being able to
pass the tests due to this (at least when other tests weren't failing),
I manually added a matching key on the slave pending any test changes.

In looking around, since this test is specifically part of the
msvc9compiler test module, thus presumably we know that VC9 (VS2008) is
installed, how about a key that is VC9 specific?  It would appear that
"HKCU\Software\Microsoft\VisualStudio\9.0\VC\Build Timing" (DWORD,
default 0) is present on a brand new VS 2008 install.  It's also present
in both the full VS version as well as express.

If the test also needs to support VC8 (VS2005), the same key is present
but under "8.0" rather than "9.0" so the test would need to pass if
either worked.

(Oh, and a correction to my last comment about HKCU - I missed that the
Reg.get_value() in the failing part of the test checks multiple roots,
not just HKCU).