$OpenBSD$

Version the SO.

Index: src/CMakeLists.txt
--- src/CMakeLists.txt.orig
+++ src/CMakeLists.txt
@@ -4,6 +4,7 @@ file(GLOB lily_SOURCES *.c *.h)
 # library. The two use the same sources, put together in an object library.
 add_library(liblily_obj OBJECT ${lily_SOURCES})
 add_library(liblily SHARED $<TARGET_OBJECTS:liblily_obj>)
+set_target_properties(liblily PROPERTIES SOVERSION ${LIBlily_VERSION})
 
 if(NOT MSVC)
     if(LILY_NEED_DL)
