newt/builder: Add SDK private includes support

[m-gorecki]

This allows specifying include directories that will only be used internally in the SDK package.
Usage example (in pkg.yml):

pkg.private_include_dirs:

• "example/directory1"
• "example/directory2"

[kasjer]

LGTM

[sjanc]

Hmm doesn't seem to work for me (notice @osdp in include list not being expanded to repos/osdp)

repository.osdp:
    type: github
    vers: v3.2.1-commit
    user: goToMain
    repo: libosdp

pkg.private_include_dirs:
    - "@osdp/utils/include"

pkg.source_files:
    - "@osdp/src/osdp_common.c"
    - "@osdp/src/osdp_phy.c"

arm-none-eabi-gcc -DAPP_NAME=osdp_sample -DAPP_osdp_sample -DARCH_NAME=cortex_m4 -DARCH_cortex_m4 -DBSP_NAME=nordic_pca10056 -DBSP_nordic_pca10056 -DMBEDTLS_USER_CONFIG_FILE=<mbedtls/config_mynewt.h> -DMYNEWT=1 -DNRF52840_XXAA -Os -Wall -Werror -fdata-sections -ffunction-sections -fno-common -fno-exceptions -ggdb -mcpu=cortex-m4 -mthumb -mthumb-interwork -Ibin/targets/osdp_sample/generated/include -Ibin/targets/osdp_sample/user/pre_build/include -Irepos/apache-mynewt-core/boot/startup/include -Irepos/apache-mynewt-core/crypto/mbedtls/include -Irepos/apache-mynewt-core/crypto/mbedtls/include/mbedtls -Irepos/apache-mynewt-core/crypto/tinycrypt/include -Irepos/apache-mynewt-core/encoding/tinycbor/include -Irepos/apache-mynewt-core/hw/bsp/nordic_pca10056/include -Irepos/apache-mynewt-core/hw/bsp/nordic_pca10056/include/bsp -Irepos/apache-mynewt-core/hw/cmsis-core/include -Irepos/apache-mynewt-core/hw/drivers/trng/include -Irepos/apache-mynewt-core/hw/drivers/trng/trng_nrf52/include -Irepos/apache-mynewt-core/hw/drivers/uart/include -Irepos/apache-mynewt-core/hw/drivers/uart/uart_hal/include -Irepos/apache-mynewt-core/hw/hal/include -Irepos/apache-mynewt-core/hw/mcu/nordic/include -Irepos/apache-mynewt-core/hw/mcu/nordic/nrf52xxx/include -Irepos/apache-mynewt-core/hw/mcu/nordic/nrf_common/include -Irepos/apache-mynewt-core/kernel/os/include -Irepos/apache-mynewt-core/kernel/os/include/os/arch/cortex_m4 -Irepos/apache-mynewt-core/libc/baselibc/include -Irepos/apache-mynewt-core/net/osdp/include -Irepos/apache-mynewt-core/net/osdp/src -Irepos/apache-mynewt-core/sys/console/full/include -Irepos/apache-mynewt-core/sys/defs/include -Irepos/apache-mynewt-core/sys/flash_map/include -Irepos/apache-mynewt-core/sys/log/common/include -Irepos/apache-mynewt-core/sys/log/full/include -Irepos/apache-mynewt-core/sys/log/modlog/include -Irepos/apache-mynewt-core/sys/sys/include -Irepos/apache-mynewt-core/sys/sysdown/include -Irepos/apache-mynewt-core/sys/sysinit/include -Irepos/apache-mynewt-core/time/datetime/include -Irepos/apache-mynewt-core/util/cbmem/include -Irepos/apache-mynewt-core/util/mem/include -Irepos/apache-mynewt-core/util/rwlock/include -Irepos/apache-mynewt-mcumgr/cborattr/include -Irepos/mcuboot/boot/bootutil/include -Irepos/mcuboot/boot/mynewt/flash_map_backend/include -Irepos/mcuboot/boot/mynewt/mcuboot_config/include -I@osdp/utils/include -Irepos/arm-CMSIS_5/CMSIS/Core/Include -Irepos/arm-CMSIS_5/CMSIS/DSP/Include -Irepos/mbedtls/include -Irepos/mbedtls/library -Irepos/nordic-nrfx -Irepos/nordic-nrfx/drivers -Irepos/nordic-nrfx/drivers/include -Irepos/nordic-nrfx/drivers/src -Irepos/nordic-nrfx/hal -Irepos/nordic-nrfx/helpers -Irepos/nordic-nrfx/mdk -Irepos/osdp/include -Irepos/osdp/src -c -o /home/janc/devel/mynewt/bin/targets/osdp_sample/app/@apache-mynewt-core/net/osdp/repos/osdp/src/osdp_common.o repos/osdp/src/osdp_common.c