$NetBSD$

Install man-pages into proper directory.

--- doc/CMakeLists.txt.orig	2014-09-24 06:37:24.000000000 +0000
+++ doc/CMakeLists.txt
@@ -96,5 +96,7 @@ else (XMLMANTOHTML_EXECUTABLE)
     COMMAND echo "[Error: xmlmantohtml required to see manpage here]" > omp.html)
 endif (XMLMANTOHTML_EXECUTABLE)
 
+include(GNUInstallDirs)
+
 install (FILES omp.8
-  DESTINATION ${DATADIR}/man/man8 )
+  DESTINATION ${CMAKE_INSTALL_MANDIR}/man8 )