We are currently experiencing sporadic CI full build failures of optee-
ftpm-stm32mp15x package ("nocross" build):

```
make[3]: *** No rule to make target
'lib/wolf/wolf_symlink/wolfcrypt/src/aes.c', needed by
'../out/fTPM/./lib/wolf/wolf_symlink/wolfcrypt/src/aes.o'.  Stop.
```

I'm just wondering if this is something known and there might be a fix,
or we should investigate it.

For details, I'm attaching two build logs from `tmp/work/debian-
bullseye-armhf/optee-os-stm32mp15x/3.21.0-r0/`. They are both received
for the same isar revision, but one is OK while another got failed.

Initially, this was observed on top of "imager-schroot" + "base-apt"
patchsets, but it also appears to happen with current "next" branch.