Set SOVERSION to 4 for CMake builds

In aa79fc2, the SOVERSION was bumped to 4 for autoconf-based builds,
but was left at 3 for CMake builds.  This shouldn't differ based on
which tool is used to build msgpack-c.

Signed-off-by: James McCoy <[email protected]>

Author: jamessan

CMakeLists.txt

@@ -264,7 +264,7 @@ ADD_LIBRARY (msgpack-static STATIC
 SET_TARGET_PROPERTIES (msgpack-static PROPERTIES OUTPUT_NAME "msgpack")
 IF (MSGPACK_ENABLE_SHARED)
     SET_TARGET_PROPERTIES (msgpack PROPERTIES IMPORT_SUFFIX "_import.lib")
-    SET_TARGET_PROPERTIES (msgpack PROPERTIES SOVERSION 3 VERSION 4.0.0)
+    SET_TARGET_PROPERTIES (msgpack PROPERTIES SOVERSION 4 VERSION 4.0.0)
 ENDIF ()
 
 IF (MSGPACK_BUILD_TESTS)