cmake: for vscode launch fallback to gdb-multiarch

Newer toolchains don't ship with arm-none-eabi-gdb hence we should use gdb-multiarch instead

platforms/nuttx/CMakeLists.txt

@@ -506,6 +506,11 @@ if(NOT NUTTX_DIR MATCHES "external")
 		message(STATUS "Found SVD: ${DEBUG_SVD_FILE_PATH}")
 	endif()
 
+	if(NOT CMAKE_GDB)
+		find_program(CMAKE_GDB gdb-multiarch)
+		message(STATUS "Found GDB: ${CMAKE_GDB}")
+	endif()
+
 	if(DEBUG_DEVICE)
 		configure_file(${CMAKE_CURRENT_SOURCE_DIR}/Debug/launch.json.in ${PX4_SOURCE_DIR}/.vscode/launch.json @ONLY)
 	endif()