This device requires additional patches to the sources of ROM. You can find them here: "https://github.com/andixlm/android_build-tools_galaxys2plus-common/tree/cm-12.1/patches". If you follow "How to build" instruction the repo "android_build-tools_galaxys2plus-common" will be downloaded into "build-tools" folder in the root of ROM's directory.
Initialize repo:
repo init -u git://github.com/CyanogenMod/android.git -b cm-12.1
curl --create-dirs -L -o .repo/local_manifests/manifest_samsung_galaxys2plus-common.xml -O -L https://raw.githubusercontent.com/andixlm/android_device_samsung_galaxys2plus-common/cm-12.1/manifest/manifest_samsung_galaxys2plus-common.xml
repo sync
Compile:
cd build-tools
./resync
./patch
./build s2plus