CMake Failure - no rule to make ctwm.1.xml on OpenSuSe Leap 42.3

I'm attempting to compile ctwm 4.0.1 on OpenSuSe Leap 42.3, because the previous versions of ctwm that I've tried (3.8.1 & 3.8.2) both tend to crash X windows when I'm running them. This is new, as they worked fine under Leap 42.2 and it's only the new version that has broken them.

In any case, when I attempt to build 4.0.1 I get the error :

"Scanning dependencies of target man"
...
make[3]: *** No rule to make target 'ctwm1.xml', needed by 'ctwm.1'. Stop.
...

This of course causes the recipe for man.dir/all to fail, and stops the compile. This is even though I went to the trouble of installing Doxygen. What other dependencies are there for the .xml file?

Interesting notes from the make are that when it runs "xmlto" you get a CMake warning "Using xmlto manpage generation. This will compromise the quality of PDF output" but that is only a warning (in cmake_files/find_asciidoc_bits.cmake:316). It lists the following call stack :

  cmake_files/handle_manual.cmake:159 (xmlto_mk_manpage)
  CMakeLists.txt:115 (include)

Is this returning a non-zero value, causing some sort of apparent failure? I haven't spent a lot of time digging into this, because it's been a long time since I dealt with make directly but I cannot easily find a way to skip the whole manpage target and just move on to try to compile everything (which I really would like).

  Thanks, Mowgli