libgcc: remove unused package

`libgcc` is not usable as is and as a result no packages use it today.
`gcc.cc.libgcc` should provide the same library. But ideally it should
not be used at all as it's an implementation detail of `gcc` support
libraries.

pkgs/top-level/aliases.nix

@@ -841,6 +841,7 @@ mapAliases ({
   liberation_ttf_v1_from_source = throw "'liberation_ttf_v1_from_source' has been renamed to/replaced by 'liberation_ttf_v1'"; # Converted to throw 2022-02-22
   liberation_ttf_v2_from_source = throw "'liberation_ttf_v2_from_source' has been renamed to/replaced by 'liberation_ttf_v2'"; # Converted to throw 2022-02-22
   liberationsansnarrow = throw "'liberationsansnarrow' has been renamed to/replaced by 'liberation-sans-narrow'"; # Converted to throw 2022-02-22
+  libgcc = throw "libgcc was removed, use gcc.cc.libgcc if needed"; # added 2023-05-13
   libgksu = throw "libgksu has been removed"; # Added 2022-01-16
   libgme = game-music-emu; # Added 2022-07-20
   libgnome_keyring = throw "'libgnome_keyring' has been renamed to/replaced by 'libgnome-keyring'"; # Converted to throw 2022-02-22

pkgs/top-level/all-packages.nix

@@ -18018,10 +18018,6 @@ with pkgs;
 
   librarian-puppet-go = callPackage ../development/tools/librarian-puppet-go { };
 
-  libgcc = callPackage ../development/libraries/gcc/libgcc {
-    stdenvNoLibs = gccStdenvNoLibs; # cannot be built with clang it seems
-  };
-
   # This is for e.g. LLVM libraries on linux.
   gccForLibs =
     if stdenv.targetPlatform == stdenv.hostPlatform && targetPackages.stdenv.cc.isGNU