cmake: check for optional libsystemd presence

CMake/FindLibsystemd.cmake

@@ -0,0 +1,28 @@
+include(FindPkgConfig)
+pkg_check_modules(PC_SYSTEMD QUIET "libsystemd")
+if (PC_SYSTEMD_FOUND)
+	add_definitions(${PC_SYSTEMD_CFLAGS} ${PC_SYSTEMD_CFLAGS_OTHER})
+endif(PC_SYSTEMD_FOUND)
+
+find_path(
+    SYSTEMD_INCLUDE_DIRS
+    NAMES systemd/sd-daemon.h
+    HINTS ${PC_SYSTEMD_INCLUDEDIR} ${PC_SYSTEMD_INCLUDE_DIRS}
+)
+
+find_library(
+    SYSTEMD_LIBRARIES
+    NAMES systemd
+    HINTS ${PC_SYSTEMD_LIBDIR} ${PC_SYSTEMD_LIBRARY_DIRS}
+)
+
+include(FindPackageHandleStandardArgs)
+
+find_package_handle_standard_args(
+    SYSTEMD
+    REQUIRED_VARS SYSTEMD_LIBRARIES SYSTEMD_INCLUDE_DIRS
+)
+mark_as_advanced(
+    SYSTEMD_FOUND
+    SYSTEMD_LIBRARIES SYSTEMD_INCLUDE_DIRS
+)

CMakeLists.txt

@@ -757,6 +757,14 @@ if(ENABLE_WX)
   endif()
 endif()
 
+find_package(Libsystemd)
+if(SYSTEMD_FOUND)
+  message(STATUS "libsystemd found, enabling traversal server watchdog support")
+  add_definitions(-DHAVE_LIBSYSTEMD)
+else()
+  message(STATUS "libsystemd not found, disabling traversal server watchdog support")
+endif()
+
 ########################################
 # Pre-build events: Define configuration variables and write SCM info header
 #