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/make-symlinks-relative.sh

@@ -0,0 +1,28 @@
+fixupOutputHooks+=(_makeSymlinksRelative)
+
+# For every symlink in $output that refers to another file in $output
+# ensure that the symlink is relative. This removes references to the output
+# has from the resulting store paths and thus the NAR files.
+_makeSymlinksRelative() {
+    local symlinkTarget
+
+    if [ -n "${dontRewriteSymlinks-}" ]; then
+        return 0
+    fi
+
+    while IFS= read -r -d $'\0' f; do
+        symlinkTarget=$(readlink "$f")
+        if [[ "$symlinkTarget"/ != "$prefix"/* ]]; then
+            # skip this symlink as it doesn't point to $prefix
+            continue
+        fi
+
+        if [ ! -e "$symlinkTarget" ]; then
+            echo "the symlink $f is broken, it points to $symlinkTarget (which is missing)"
+        fi
+
+        echo "rewriting symlink $f to be relative to $prefix"
+        ln -snrf "$symlinkTarget" "$f"
+
+    done < <(find $prefix -type l -print0)
+}