Add VERSION property to CMake library targets

cmake/libprotobuf.cmake

diff --git a/cmake/libprotobuf.cmake b/cmake/libprotobuf.cmake
index 72db915..e07340d 100644
--- a/cmake/libprotobuf.cmake
+++ b/cmake/libprotobuf.cmake
@@ -125,5 +125,6 @@
     PRIVATE LIBPROTOBUF_EXPORTS)
 endif()
 set_target_properties(libprotobuf PROPERTIES
+    VERSION ${protobuf_VERSION}
     OUTPUT_NAME ${LIB_PREFIX}protobuf
     DEBUG_POSTFIX "${protobuf_DEBUG_POSTFIX}")