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/pkg-config-wrapper/add-flags.sh

@@ -0,0 +1,12 @@
+# See cc-wrapper for comments.
+var_templates_list=(
+    PKG_CONFIG_PATH
+)
+
+accumulateRoles
+
+for var in "${var_templates_list[@]}"; do
+    mangleVarListGeneric ":" "$var" ${role_suffixes[@]+"${role_suffixes[@]}"}
+done
+
+export NIX_PKG_CONFIG_WRAPPER_FLAGS_SET_@suffixSalt@=1