Fix includedir

noson-app code uses `<noson/*.h>`, so building that against noson as
system library will fail as `<noson/noson/*.h>` does not exist.

This is the case on OpenBSD where /usr/local/ is the default prefix.
On Linux, the default is /usr/, i.e. the same as the default prefix.

My guess it's been working by accident so far.

Author: klemensn

noson/CMakeLists.txt

@@ -398,7 +398,7 @@ if (NOT SKIP_INSTALL_ALL)
     endif ()
     set (prefix      "${CMAKE_INSTALL_PREFIX}")
     set (exec_prefix "${CMAKE_INSTALL_PREFIX}")
-    set (includedir  "${CMAKE_INSTALL_INCLUDEDIR}/noson")
+    set (includedir  "${CMAKE_INSTALL_INCLUDEDIR}")
     set (libdir      "${CMAKE_INSTALL_FULL_LIBDIR}")
     configure_file (noson.pc.in noson.pc @ONLY)
     configure_file (nosonConfig.cmake.in nosonConfig.cmake @ONLY)