move to new build system

cmake/libraries/libevent.cmake

@@ -0,0 +1,40 @@
+if(PROJECT_ENABLE_LIBEVENT)
+  if(PROJECT_BUILD)
+    find_package(Libevent ${LIBEVENT_VERSION} REQUIRED)
+
+    add_definitions(-DPROJECT_ENABLE_LIBEVENT)
+
+    include_directories(BEFORE SYSTEM
+      ${LIBEVENT_INCLUDE_DIRS}
+    )
+
+    link_libraries(
+      ${LIBEVENT_LIBRARIES}
+    )
+  elseif(NOT PROJECT_IS_MINGW OR CMAKE_HOST_WIN32)
+    if(PROJECT_BUILD_SHARED_LIBS)
+      set(LIBEVENT_LIBRARY_TYPE BOTH)
+    else()
+      set(LIBEVENT_LIBRARY_TYPE STATIC)
+    endif()
+
+    ExternalProject_Add(libevent_project
+      PREFIX external
+      URL ${PROJECT_3RD_PARTY_DIR}/libevent-${LIBEVENT_VERSION}-stable.tar.gz
+      URL_HASH SHA256=92e6de1be9ec176428fd2367677e61ceffc2ee1cb119035037a27d346b0403bb
+      LIST_SEPARATOR |
+      CMAKE_ARGS ${PROJECT_EXTERNAL_CMAKE_FLAGS}
+        -DBUILD_SHARED_LIBS=${PROJECT_BUILD_SHARED_LIBS}
+        -DBUILD_STATIC_LIBS=ON
+        -DEVENT__DISABLE_OPENSSL=ON
+        -DEVENT__DISABLE_SAMPLES=ON
+        -DEVENT__DISABLE_TESTS=ON
+        -DEVENT__LIBRARY_TYPE=${LIBEVENT_LIBRARY_TYPE}
+    )
+
+    set(PROJECT_DEPENDENCIES 
+      ${PROJECT_DEPENDENCIES}
+      libevent_project
+    )
+  endif()
+endif()