VisualStudio: Remove MSVC6 compatibility macro.

Source/cmCallVisualStudioMacro.cxx

@@ -34,8 +34,6 @@ static bool LogErrorsAsMessages;
 // Copied from a correct comdef.h to avoid problems with deficient versions
 // of comdef.h that exist in the wild... Fixes issue #7533.
 //
-#if ( _MSC_VER >= 1300 )
-// VS7 and later:
 #ifdef _NATIVE_WCHAR_T_DEFINED
 # ifdef _DEBUG
 # pragma comment(lib, "comsuppwd.lib")
@@ -49,10 +47,6 @@ static bool LogErrorsAsMessages;
 # pragma comment(lib, "comsupp.lib")
 # endif
 #endif
-#else
-// VS6 only had comsupp.lib:
-# pragma comment(lib, "comsupp.lib")
-#endif
 
 
 //----------------------------------------------------------------------------