[ng] rename: am__dist_* -> am.dist.*

[ng] rename: am__dist_* -> am.dist.*

Here is the complete list of renames:

    am__dist_common        ->   am.dist.common-files
    am__dist_sources       ->   am.dist.sources
    am__dist_files         ->   am.dist.all-files
    am__dist_files_1       ->   am.dist.files-tmp1
    am__dist_files_2       ->   am.dist.files-tmp2
    am__dist_files_cooked  ->   am.dist.files-cooked
    am__dist_parent_dirs   ->   am.dist.parent-dirs

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>