util/StringCompare: add missing include

src/util/StringCompare.cxx

 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions

src/util/StringCompare.hxx

 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -38,6 +38,8 @@
 #include "WStringCompare.hxx"
 #endif
 
+#include <string_view>
+
 gcc_pure gcc_nonnull_all
 static inline bool
 StringIsEmpty(const char *string) noexcept

src/util/WStringCompare.cxx

 /*
- * Copyright 2013-2019 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions

src/util/WStringCompare.hxx

 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -34,6 +34,8 @@
 #include "WStringAPI.hxx"
 #include "Compiler.h"
 
+#include <string_view>
+
 #include <wchar.h>
 
 gcc_pure gcc_nonnull_all