gcc: disable glibc<->libgcc circularity workaround for windows and LLVM

This essentially reverts #238154 if `isWindows` or `useLLVM`, the
two cases where it caused breakage:

  https://github.com/NixOS/nixpkgs/pull/238154#issuecomment-1633752094

Since #238154 exists mainly for `isGNU` (i.e. due to the
glibc<->libgcc circular dependency) disabling it here isn't a big deal.

pkgs/development/compilers/gcc/common/libgcc.nix

@@ -19,7 +19,7 @@ drv: lib.pipe drv
   (pkg: pkg.overrideAttrs (previousAttrs:
     lib.optionalAttrs (
       targetPlatform != hostPlatform &&
-      enableShared &&
+      (enableShared || targetPlatform.libc == "msvcrt") &&
       withoutTargetLibc
     ) {
       makeFlags = [ "all-gcc" "all-target-libgcc" ];
@@ -40,6 +40,7 @@ lib.optional (lib.versionAtLeast version "11.0")
     else "${targetPlatform.config}/";
 
   enableLibGccOutput =
+    (!stdenv.targetPlatform.isWindows || (with stdenv; targetPlatform == hostPlatform)) &&
     !langJit &&
     !stdenv.hostPlatform.isDarwin &&
     enableShared

pkgs/top-level/all-packages.nix

@@ -15369,6 +15369,14 @@ with pkgs;
         langCC = false;
         libcCross = libcCross1;
         targetPackages.stdenv.cc.bintools = binutilsNoLibc;
+        enableShared =
+          stdenv.targetPlatform.hasSharedLibraries
+
+          # temporarily disabled due to breakage;
+          # see https://github.com/NixOS/nixpkgs/pull/243249
+          && !stdenv.targetPlatform.isWindows
+          && !(stdenv.targetPlatform.useLLVM or false)
+        ;
       };
       bintools = binutilsNoLibc;
       libc = libcCross1;