[CMake] _USRDLL issue with Extension DLLs in MSVC6.0

[shabelnikov at secu-3.org]

Hello All,

I faced issue with Visual Studio 6.0 project (.dsp) produced by CMake.
CMake version: 2.8.6
Project type: Extension DLL
Issue: CMake adds _USRDLL define for Extension DLLs (_AFXDLL and 
_AFXEXT are defined). According to documentation 
(http://msdn.microsoft.com/en-us/library/aa235516%28v=vs.60%29.aspx) 
_USRDLL must not be defined for Extension DLLs (when _AFXDLL is 
defined). This behavior leads to linker errors.
Solution that I see: exclude _USRDLL symbol when _AFXDLL & _AFXEXT 
symbols are defined.

Additionally:
I've also tested my project with Visual Studio 9 and it works OK;
I've tried several ways to make CMake do not add mentioned symbol to 
produced project but without success;
I've checked CMake 2.8.6 source code and found that _USRDLL symbol 
persists in DLLHeader.dsptemplate project template.

p.s. I've searched documentation, FAQ, ChangeLog.txt and web for this 
issue and haven't found answer.

Best Regards,
Alexey Shabelnikov