It turns out that with the release of Windows 8 and the subsequent change to the credential providers, starting with Visual Studio 2012, the constant CLSID_PasswordCredentialProvider began to point to the v2 Password Credential Provider rather than the v1 Password Credential Provider (the version that Windows 7 uses). So in order to get the wrapped credential provider sample to compile correctly, which was the one that I was testing, it was necessary to change the following line in CSampleProvider.cpp:
hr = CoCreateInstance(CLSID_PasswordCredentialProvider, NULL, CLSCTX_ALL, IID_PPV_ARGS(&pUnknown));
to instead point to the V1 credential provider:
hr = CoCreateInstance(CLSID_V1PasswordCredentialProvider, NULL, CLSCTX_ALL, IID_PPV_ARGS(&pUnknown));
Once this was done and the project was recompiled and installed it worked as expected.
Additional information about this problem can be found at: http://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/376d6eb6-1a40-4721-abdc-27870966a1da/how-can-i-build-the-windows-7-credential-provider-samples-using-visual-studio-2012?forum=windowsgeneraldevelopmentissues