botan3: fix static cli build through empty-libgcc_eh workaround

Prior to this commit the build of `pkgsStatic.botan3.bin` produced a
dynamically linked binary, indenpendently of the move to
`pkgs/by-name`. Previous commit message and comments also suggest this
it was expected for the static build to only produce the static library,
not the statically linked cli.

pkgs/by-name/bo/botan3/package.nix

@@ -4,6 +4,8 @@
   libcxxStdenv,
   fetchurl,
   pkgsStatic,
+  runCommandLocal,
+  binutils,
   python3,
   docutils,
   bzip2,
@@ -11,7 +13,7 @@
   jitterentropy,
   esdm,
   tpm2-tss,
-  static ? stdenv.hostPlatform.isStatic, # generates static libraries *only*
+  static ? stdenv.hostPlatform.isStatic,
   windows,
 
   # build ESDM RNG plugin
@@ -33,6 +35,21 @@ assert lib.assertOneOf "policy" policy [
 ];
 let
   stdenv = if static then libcxxStdenv else args.stdenv;
+
+  # (based on same workaround from capnproto package)
+  #
+  # HACK: work around https://github.com/NixOS/nixpkgs/issues/177129
+  # Though this is an issue between Clang and GCC,
+  # so it may not get fixed anytime soon...
+  empty-libgcc_eh =
+    runCommandLocal "empty-libgcc_eh"
+      {
+        nativeBuildInputs = [ binutils ];
+      }
+      ''
+        mkdir -p "$out"/lib
+        ${stdenv.cc.targetPrefix}ar r "$out"/lib/libgcc_eh.a
+      '';
 in
 stdenv.mkDerivation (finalAttrs: {
   version = "3.9.0";
@@ -80,6 +97,8 @@ stdenv.mkDerivation (finalAttrs: {
     windows.pthreads
   ];
 
+  propagatedBuildInputs = lib.optional static empty-libgcc_eh;
+
   buildTargets = [
     "cli"
   ]