Build: Switch to CMake :^)

Closes https://github.com/SerenityOS/serenity/issues/2080

Libraries/LibGfx/CMakeLists.txt

@@ -0,0 +1,26 @@
+set(SOURCES
+    AffineTransform.cpp
+    Bitmap.cpp
+    CharacterBitmap.cpp
+    Color.cpp
+    DisjointRectSet.cpp
+    Emoji.cpp
+    FloatRect.cpp
+    Font.cpp
+    GIFLoader.cpp
+    ImageDecoder.cpp
+    Painter.cpp
+    Palette.cpp
+    Path.cpp
+    PNGLoader.cpp
+    Point.cpp
+    Rect.cpp
+    ShareableBitmap.cpp
+    Size.cpp
+    StylePainter.cpp
+    SystemTheme.cpp
+    Triangle.cpp
+)
+
+serenity_lib(LibGfx gfx)
+target_link_libraries(LibGfx LibM LibCore)