cmake: prefer system libraries

externals/find-modules/Findenet.cmake

@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: 2022 Alexandre Bouvier <contact@amb.tf>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+find_package(PkgConfig QUIET)
+if (PKG_CONFIG_FOUND)
+    pkg_search_module(ENET QUIET IMPORTED_TARGET GLOBAL libenet)
+    if (ENET_FOUND)
+        add_library(enet::enet ALIAS PkgConfig::ENET)
+    endif()
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(enet
+    REQUIRED_VARS ENET_LINK_LIBRARIES
+    VERSION_VAR ENET_VERSION
+)