VS: Add a variable to report the Visual Studio version build number

VS 2017 and above come with a Visual Studio Installer tool that tracks
four-component Visual Studio version numbers.  We already detect the VS
version number because it is needed to make some generation decisions.
Provide the number to projects in a `CMAKE_VS_VERSION_BUILD_NUMBER`
variable so they can use it similarly.

Fixes: #24230

1 files changed, 1 insertions, 0 deletions

diff --git a/Source/cmGlobalVisualStudioVersionedGenerator.h b/Source/cmGlobalVisualStudioVersionedGenerator.h
index 4c69aeb2ed..45aca74a80 100644
--- a/Source/cmGlobalVisualStudioVersionedGenerator.h
+++ b/Source/cmGlobalVisualStudioVersionedGenerator.h
@@ -93,6 +93,7 @@ private:
   mutable cmVSSetupAPIHelper vsSetupAPIHelper;
 
   bool ParseGeneratorInstance(std::string const& is, cmMakefile* mf);
+  void SetVSVersionVar(cmMakefile* mf);
 
   std::string GeneratorInstance;
   std::string GeneratorInstanceVersion;