Fix build on Visual Studio Express.

Fix build on Visual Studio Express.

Visual Studio Express doesn't ship with MFC so the afxres.h header isn't
available.  Since we don't actually use it, it's safe to replace that
header with a standard #include and #define.

Note that Visual Studio Express also ships without mc.exe so you will
also need to download the Windows SDK and set up your PATH in order to
build NSSM.