feat(zephyr): support v4.4

- fix(cmake): only create alias if it doesn't exist:
Zephyr v4.4 has moved to MbedTLS 4.x in following PR:
https://github.com/zephyrproject-rtos/zephyr/pull/104031
Zephyr now uses MbedTLS' CMakeLists, which exports targets
with NAMESPACE MbedTLS::, therefore MbedTLS::mbedtls,
MbedTLS::mbedx509, MbedTLS::tfpsacrypto aliases already exist

- fix(zephyr): v4.4: include correct mbedtls config based on zephyr version
CONFIG_MBEDTLS_CFG_FILE was deprecated. Instead, CONFIG_MBEDTLS_CONFIG_FILE
shall be used. This change supports both based on Kconfig symbols.

Signed-off-by: Krisztian Szilvasi <34309983+kr-t@users.noreply.github.com>

CMakeLists.txt

@@ -801,9 +801,17 @@ target_compile_options(
   PUBLIC -DLIBCOAP_PACKAGE_BUILD="${LIBCOAP_PACKAGE_BUILD}")
 
 if(ZEPHYR_BASE)
-target_compile_options(
-  ${COAP_LIBRARY_NAME}
-  PUBLIC -DMBEDTLS_CONFIG_FILE="${CONFIG_MBEDTLS_CFG_FILE}" -I${ZEPHYR_MBEDTLS_CMAKE_DIR}/configs)
+  # Zephyr >= v4.4:
+  if(DEFINED CONFIG_MBEDTLS_CONFIG_FILE)
+    target_compile_options(${COAP_LIBRARY_NAME}
+      PUBLIC -DMBEDTLS_CONFIG_FILE="${CONFIG_MBEDTLS_CONFIG_FILE}" -I${ZEPHYR_MBEDTLS_CMAKE_DIR}/configs)
+  # Zephyr < v4.4:
+  elseif(DEFINED CONFIG_MBEDTLS_CFG_FILE)
+    target_compile_options(${COAP_LIBRARY_NAME}
+      PUBLIC -DMBEDTLS_CONFIG_FILE="${CONFIG_MBEDTLS_CFG_FILE}" -I${ZEPHYR_MBEDTLS_CMAKE_DIR}/configs)
+  else()
+    message(WARNING "No usable MBEDTLS config Kconfig symbol found")
+  endif()
 endif() # ! ZEPHYR_BASE
 
 add_library(

zephyr/CMakeLists.txt

@@ -159,7 +159,10 @@ if(CONFIG_LIBCOAP)
   if(CONFIG_MBEDTLS)
     if(TARGET mbedTLS)
       target_include_directories(mbedTLS INTERFACE ${ZEPHYR_LIBCOAP_MODULE_DIR}/include)
-      add_library(MbedTLS::mbedtls ALIAS mbedTLS)
+      # Only create alias if it doesn't already exist (Zephyr v4.4+ has it)
+      if(NOT TARGET MbedTLS::mbedtls)
+        add_library(MbedTLS::mbedtls ALIAS mbedTLS)
+      endif()
     else()
       message(WARNING "mbedTLS target not found.")
     endif()