LibCore: Use the Linux implementation of TimeZoneWatcher on BSDs

The same implementation works just fine on any BSD system provided it
has a working FileWatcher implementation.

Libraries/LibCore/CMakeLists.txt

@@ -92,25 +92,21 @@ endif()
 
 # FIXME: Implement ProcessStatistics for Windows and *BSD
 if (LINUX)
-    list(APPEND SOURCES
-        Platform/ProcessStatisticsLinux.cpp
-        TimeZoneWatcherLinux.cpp
-    )
+    list(APPEND SOURCES Platform/ProcessStatisticsLinux.cpp)
 elseif (APPLE AND NOT IOS)
-    list(APPEND SOURCES
-        Platform/ProcessStatisticsMach.cpp
-        TimeZoneWatcherMacOS.mm
-    )
+    list(APPEND SOURCES Platform/ProcessStatisticsMach.cpp)
+else ()
+    list(APPEND SOURCES Platform/ProcessStatisticsUnimplemented.cpp)
+endif()
+
+if (LINUX OR BSD)
+    list(APPEND SOURCES TimeZoneWatcherUnix.cpp)
+elseif (APPLE AND NOT IOS)
+    list(APPEND SOURCES TimeZoneWatcherMacOS.mm)
 elseif (WIN32)
-    list(APPEND SOURCES
-        Platform/ProcessStatisticsUnimplemented.cpp
-        TimeZoneWatcherWindows.cpp
-    )
+    list(APPEND SOURCES TimeZoneWatcherWindows.cpp)
 else()
-    list(APPEND SOURCES
-        Platform/ProcessStatisticsUnimplemented.cpp
-        TimeZoneWatcherUnimplemented.cpp
-    )
+    list(APPEND SOURCES TimeZoneWatcherUnimplemented.cpp)
 endif()
 
 if (APPLE OR CMAKE_SYSTEM_NAME STREQUAL "GNU")

Libraries/LibCore/TimeZoneWatcherUnix.cpp

@@ -8,10 +8,6 @@
 #include <LibCore/FileWatcher.h>
 #include <LibCore/TimeZoneWatcher.h>
 
-#if !defined(AK_OS_LINUX)
-static_assert(false, "This file must only be used for Linux");
-#endif
-
 namespace Core {
 
 static constexpr auto time_zone_files = Array {