pkgsStatic.strace: fix build

Static-only elfutils builds are not supported.

Fixes: a48232a475ff ("strace: 6.6 -> 6.7")

pkgs/development/tools/misc/strace/default.nix

@@ -12,9 +12,12 @@ stdenv.mkDerivation rec {
   depsBuildBuild = [ buildPackages.stdenv.cc ];
   nativeBuildInputs = [ perl ];
 
+  # libunwind for -k.
   # On RISC-V platforms, LLVM's libunwind implementation is unsupported by strace.
   # The build will silently fall back and -k will not work on RISC-V.
-  buildInputs = [ libunwind elfutils ]; # support -k and -kk
+  buildInputs = [ libunwind ]
+    # -kk
+    ++ lib.optional (lib.meta.availableOn stdenv.hostPlatform elfutils) elfutils;
 
   configureFlags = [ "--enable-mpers=check" ];