If a custom command is assigned to multiple targets, generate the build
rule only in the least-dependent `.vcxproj` file.  Otherwise MSBuild
will run the command on the first build of a dependent target even if
its dependencies already brought the command up to date (in order to
populates its build log).

Generate targets in least-to-most-dependent order, and assign a custom
command to the least dependent target.

Added cmLocalVisualStudio10Generator::GenerateTargetsDepthFirst to call
cmVisualStudio10TargetGenerator::Generate in least-dependent order.

Moved SourcesVisited from cmVisualStudio10TargetGenerator to
cmLocalVisualStudio10Generator to avoid attaching a custom command to
multiple targets among the local generator.

Fixes: #16767