cmake: handle correctly the lib extensions

CMakeLists.txt

@@ -126,7 +126,11 @@ SET(${PROJECT_NAME}_SOURCES
 )
 
 ADD_LIBRARY(${PROJECT_NAME} SHARED ${${PROJECT_NAME}_SOURCES} ${${PROJECT_NAME}_HEADERS})
-SET_TARGET_PROPERTIES(${PROJECT_NAME} PROPERTIES SUFFIX "${PYTHON_EXT_SUFFIX}")
+SET(LIB_${PROJECT_NAME}_SUFFIX ${PYTHON_EXT_SUFFIX})
+IF(APPLE)
+  STRING(REPLACE ".so" ".dylib" LIB_${PROJECT_NAME}_SUFFIX ${LIB_${PROJECT_NAME}_SUFFIX})
+ENDIF(APPLE)
+SET_TARGET_PROPERTIES(${PROJECT_NAME} PROPERTIES SUFFIX "${LIB_${PROJECT_NAME}_SUFFIX}")
 TARGET_COMPILE_OPTIONS(${PROJECT_NAME} PRIVATE $<$<CXX_COMPILER_ID:MSVC>:-bigobj>)
 
 TARGET_LINK_BOOST_PYTHON(${PROJECT_NAME})