$NetBSD$

Install man-pages into proper dir.

--- CMakeLists.txt.orig	2016-02-26 14:31:03.000000000 +0000
+++ CMakeLists.txt
@@ -343,8 +343,10 @@ add_subdirectory (doc)
 
 ## Install
 
+include(GNUInstallDirs)
+
 install (FILES doc/openvas-nasl.1
-         DESTINATION ${DATADIR}/man/man1 )
+         DESTINATION ${CMAKE_INSTALL_MANDIR}/man1 )
 
 install (FILES ${CMAKE_BINARY_DIR}/libopenvas_base.pc
          DESTINATION ${LIBDIR}/pkgconfig)