Trying to include btree with the new CMake based build system for ESP32 fails, and I suspect it's due to berkeley-db not being cmake compatible.

This is with idf v4.0.2 and micropython @ 4f53f462 (latest as of this post). I don't think the idf version matters as it's more related to including berekley-db.

I enabled btree through boards/GENERIC/mpconfigboard.h:

#define MICROPY_HW_BOARD_NAME "ESP32 module"
#define MICROPY_HW_MCU_NAME "ESP32"
#define MICROPY_PY_BTREE (1)

The build fails looking for db.h:

/micropython/extmod/modbtree.c:37:10: fatal error: db.h: No such file or directory
 #include <db.h>

db.h is provided by lib/berkeley-db-1.xx/PORT/include.

I'm not sure the best approach to resolving this, especially given it's upstream.

Is there a desire to fix this, or should be rely on building as a native module / user module?