build2-bootstrap: fix building with new clang/libcpp (#510145)

pkgs/by-name/bu/build2-bootstrap/package.nix

@@ -4,6 +4,7 @@
   fetchurl,
   buildPackages,
   fixDarwinDylibNames,
+  fetchpatch,
 }:
 stdenv.mkDerivation (finalAttrs: {
   pname = "build2-bootstrap";
@@ -15,6 +16,12 @@ stdenv.mkDerivation (finalAttrs: {
   patches = [
     # Pick up sysdirs from NIX_LDFLAGS
     ./nix-ldflags-sysdirs.patch
+    # Fix build on newer clang/libcpp
+    (fetchpatch {
+      name = "new-libcpp-fix.patch";
+      url = "https://github.com/build2/build2/commit/7cf9cece1d88cd1be283ab309f9a851bd02b43d0.patch";
+      hash = "sha256-PTo1C6Aa1L9fvjiJ08KtGgVqHMw2ZlW5LSKoripL22g=";
+    })
   ];
 
   sourceRoot = "build2-toolchain-${finalAttrs.version}/build2";