fix(dns_over_https): declare main and protocol_examples_common deps

dns_over_https/main includes time_sync.h, nvs_flash.h, esp_event.h,
esp_timer.h, and mbedtls headers. Declare nvs_flash, esp_event,
esp_timer, mbedtls and time_sync in PRIV_REQUIRES so the build is
self-describing under any build system.

Also move esp_netif from PRIV_REQUIRES to REQUIRES in
protocol_examples_common, since its public header exposes esp_netif.h.

Also add the PRIVATE keyword to target_link_libraries in the
dns_over_https component — CMake rejects mixed keyword/plain
signatures on the same target.

examples/protocols/dns_over_https/components/dns_over_https/CMakeLists.txt

@@ -3,5 +3,5 @@ idf_component_register(SRCS "dns_over_https.c" "dns_utils.c"
                     PRIV_REQUIRES nvs_flash lwip esp_event esp-tls esp_http_client)
 
 if(CONFIG_LWIP_HOOK_NETCONN_EXT_RESOLVE_CUSTOM)
-    target_link_libraries(${COMPONENT_LIB} "-u lwip_hook_netconn_external_resolve")
+    target_link_libraries(${COMPONENT_LIB} PRIVATE "-u lwip_hook_netconn_external_resolve")
 endif()

examples/protocols/dns_over_https/main/CMakeLists.txt

@@ -7,4 +7,5 @@ endif()
 
 idf_component_register(SRCS "example_dns_over_https.c"
                     INCLUDE_DIRS "."
+                    PRIV_REQUIRES time_sync nvs_flash esp_event esp_timer mbedtls
                     EMBED_TXTFILES ${cert_file})