ccache: fix tests for cross compile targets

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

···
     # Linux it uses objdump. We don't have dwarfdump packaged for
     # Darwin, so this patch updates the test to also use objdump on
     # Darwin.
+    # Additionally, when cross compiling, the correct target prefix
+    # needs to be set.
     (substituteAll {
-      src = ./force-objdump-on-darwin.patch;
-      objdump = "${binutils.bintools}/bin/objdump";
+      src = ./fix-objdump-path.patch;
+      objdump = "${binutils.bintools}/bin/${binutils.targetPrefix}objdump";
     })
   ];