Commit 9a6ff950 (Fix for bug where VS2010 did not use .obj files,
2011-04-01) assumed that if an external object is GENERATED that it is
the output of a custom command in the current target. If it is
generated by another target then VS will not automatically include the
external object in the current target. This bug was preserved by the
refactoring in the parent commit.
Instead use <None> for external objects generated by a custom command in
the current target and <Object> for all other external objects. Update
the ExternalOBJ test to cover this case.
For VS2010 if a precompiled .obj file was the output of a custom commad,
it was used as part of the build. If it was not, then VS did not
use it as part of the build. This commit updates the test to check
for this issue, and fixes the problem. This fixes bugs #0011891 and
Brad King
Bill Hoffman
Ken Martin