envsetup: Combine nested else; if into elif in check_product()

    if (echo -n $1 | grep -q -e "^lineage_") ; then

        CM_BUILD=$(echo -n $1 | sed -e 's/^lineage_//g')

        export BUILD_NUMBER=$((date +%s%N ; echo $CM_BUILD; hostname) | openssl sha1 | sed -e 's/.*=//g; s/ //g' | cut -c1-10)

    else

    elif (echo -n $1 | grep -q -e "^cm_") ; then

        # Fall back to cm_<product>

        if (echo -n $1 | grep -q -e "^cm_") ; then

        CM_BUILD=$(echo -n $1 | sed -e 's/^cm_//g')

        export BUILD_NUMBER=$((date +%s%N ; echo $CM_BUILD; hostname) | openssl sha1 | sed -e 's/.*=//g; s/ //g' | cut -c1-10)

    else

        CM_BUILD=

    fi

    fi

    export CM_BUILD

        TARGET_PRODUCT=$1 \