Fix a bad BitKeeper dependency structure for the "CMakeLists.txt" files.

They had been introduced in 5.1 and were only later backported to 5.0;
as a consequence, the files in the 5.1 tree do not depend on the 5.0 ones,
and changes in 5.0 do not propagate into the 5.1 files.

To fix this, the (previous) files in 5.1 now are deleted ("bk rm"),
and the previously deleted files depending on 5.0 are now moved to the 
respective source directories ("bk mv").
The current 5.1 contents is restored in these files.

If you need the previous history of the 5.1 files ("bk revtool"),
access those in "BitKeeper/deleted".

Contrary to the original plan, I did not introduce the name
"CMakeLists.historic" - mostly in order not to clutter the source tree.

This fixes bug#29982.