make fails with:
/bin/sed: can't read drm-mm.7: No such file or directory

looking into the man folder I can find:

Makefile     drm-kms.7     drm-memory.xml  drmAvailable.3    drmHandleEvent.xml
      drm\-gem.7
Makefile.am  drm-kms.xml   drm.7           drmAvailable.xml 
drmModeGetResources.3    drm\-mm.7
Makefile.in  drm-memory.7  drm.xml         drmHandleEvent.3 
drmModeGetResources.xml  drm\-ttm.7

Thus all MANPAGE_ALIASES contain an extra \.
Renaming the files allows the make to proceed.

System: gentoo linux, newest automake, cmake, bash...