CPack: Do not recurse through directory symlinks (#12284)

...when building CPack archive-based packages (.tar.gz and similar)

Rather, put the symlinks-to-directories into the archive as files,
and expect/trust that the things the symlinks point to are also in
the archive.

Source/CPack/cmCPackGenerator.cxx

@@ -1000,6 +1000,7 @@ int cmCPackGenerator::DoPackage()
   std::string findExpr = tempDirectory;
   findExpr += "/*";
   gl.RecurseOn();
+  gl.SetRecurseThroughSymlinks(false);
   if ( !gl.FindFiles(findExpr) )
     {
     cmCPackLogger(cmCPackLog::LOG_ERROR,