[CMake] Imported libraries lookup

[Sergey Rudchenko]

On Wed, 2009-04-22 at 10:41 -0400, Brad King wrote:
> In general the generators should never have to see any imported
> targets.
> If you have a "cmTarget*" you can always ask its IsImported() method.

Thanks, Brad. Now it's clean for we how things should be implemented.

So there is one straight problem for me: LocalGenerator uses
cmTarget::GetLinkLibraries which is a
std::vector<std::pair<std::string, LinkLibraryType> > >
So, I have no cmTarget* object there (and can't find it, since the
cmMakefile::ImportedTargets is private). I guess there should be a
method like:

cmTarget* cmMakefile::FindImportedTarget(const char* name);

What do you think?

Best regards,
Sergey