How to enable option in Makefile for specific package

Hi, There is package (domoticz) requires to enable option in libcurl e.g smtp:
in diffconfig it is:

CONFIG_LIBCURL_SMTP=y

how should it should be done in Makefile to enable this option:

  DEPENDS:= \
        +boost \
        +boost-date_time \
        +boost-system \
        +boost-thread \
        +libcurl \
        +libmosquittopp \
        +libopenssl \
        +libopenzwave \
        +libsqlite3 \
        +libstdcpp \
        +zlib

I think it should be PKG_CONFIG_DEPENDS:=

Try adding

PKG_CONFIG_DEPENDS:= CONFIG_LIBCURL_SMTP

to the domoticz Makefile.

See examples in other packages https://github.com/openwrt/openwrt/search?p=2&q=PKG_CONFIG_DEPENDS%3A%3D&unscoped_q=PKG_CONFIG_DEPENDS%3A%3D