uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/build-support/setup-hooks/prune-libtool-files.sh

@@ -0,0 +1,22 @@
+# Clear dependency_libs in libtool files for shared libraries.
+
+# Shared libraries already encode their dependencies with locations.  .la
+# files do not always encode those locations, and sometimes encode the
+# locations in the wrong Nix output. .la files are not needed for shared
+# libraries, but without dependency_libs they do not hurt either.
+
+fixupOutputHooks+=(_pruneLibtoolFiles)
+
+_pruneLibtoolFiles() {
+    if [ "${dontPruneLibtoolFiles-}" ] || [ ! -e "$prefix" ]; then
+       return
+    fi
+
+    # Libtool uses "dlname" and "library_names" fields for shared libraries and
+    # the "old_library" field for static libraries.  We are processing only
+    # those .la files that do not describe static libraries.
+    find "$prefix" -type f -name '*.la' \
+         -exec grep -q '^# Generated by .*libtool' {} \; \
+         -exec grep -q "^old_library=''" {} \; \
+         -exec sed -i {} -e "/^dependency_libs='[^']/ c dependency_libs='' #pruned" \;
+}