realesrgan-ncnn-vulkan: drop redundant libgcc dependency

`libgcc` should normally be provided by `gcc` `stdenv` directly.
Checked with `diffoscope` that final output did not change.

While at it added all platforms to supported list.

pkgs/tools/graphics/realesrgan-ncnn-vulkan/default.nix

@@ -7,7 +7,6 @@
 , vulkan-headers
 , vulkan-loader
 , glslang
-, libgcc
 , libwebp
 , ncnn
 }:
@@ -44,8 +43,7 @@ stdenv.mkDerivation rec {
   ];
 
   nativeBuildInputs = [ cmake ];
-  buildInputs = [ vulkan-headers vulkan-loader glslang libwebp ncnn ]
-    ++ lib.optional (!stdenv.isDarwin) libgcc;
+  buildInputs = [ vulkan-headers vulkan-loader glslang libwebp ncnn ];
 
   postPatch = ''
     substituteInPlace main.cpp --replace REPLACE_MODELS $out/share/models
@@ -62,5 +60,6 @@ stdenv.mkDerivation rec {
     homepage = "https://github.com/xinntao/Real-ESRGAN-ncnn-vulkan";
     license = licenses.mit;
     maintainers = with maintainers; [ tilcreator ];
+    platforms = platforms.all;
   };
 }