LibGfx: Move FourCC to its own file

These are used in fonts too, so let's not limit them to ImageLoader.

Userland/Libraries/LibGfx/FourCC.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace Gfx {
+
+struct FourCC {
+    constexpr FourCC(char const* name)
+    {
+        cc[0] = name[0];
+        cc[1] = name[1];
+        cc[2] = name[2];
+        cc[3] = name[3];
+    }
+
+    bool operator==(FourCC const&) const = default;
+    bool operator!=(FourCC const&) const = default;
+
+    char cc[4];
+};
+
+}

Userland/Libraries/LibGfx/ImageFormats/ILBMLoader.cpp

@@ -8,6 +8,7 @@
 #include <AK/Debug.h>
 #include <AK/Endian.h>
 #include <AK/FixedArray.h>
+#include <LibGfx/FourCC.h>
 #include <LibGfx/ImageFormats/ILBMLoader.h>
 
 namespace Gfx {

Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.h

@@ -84,19 +84,4 @@ private:
     NonnullOwnPtr<ImageDecoderPlugin> mutable m_plugin;
 };
 
-struct FourCC {
-    constexpr FourCC(char const* name)
-    {
-        cc[0] = name[0];
-        cc[1] = name[1];
-        cc[2] = name[2];
-        cc[3] = name[3];
-    }
-
-    bool operator==(FourCC const&) const = default;
-    bool operator!=(FourCC const&) const = default;
-
-    char cc[4];
-};
-
 }

Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp

@@ -9,6 +9,7 @@
 #include <AK/Format.h>
 #include <AK/MemoryStream.h>
 #include <AK/Vector.h>
+#include <LibGfx/FourCC.h>
 #include <LibGfx/ImageFormats/WebPLoader.h>
 #include <LibGfx/ImageFormats/WebPLoaderLossless.h>
 #include <LibGfx/ImageFormats/WebPLoaderLossy.h>