Espressif SDK v2.2.1

[nwf]

Minimally build and boot tested, but the changes look pretty boring.
Fixes #2395

• This PR is for the dev branch rather than for master.
• This PR is compliant with the other contributing guidelines as well (if not, please describe why).

[devsaurus]

Looks good.

Espressif missed to update ESP_SDK_VERSION_PATCH to 1 in https://github.com/espressif/ESP8266_NONOS_SDK/blob/v2.2.1/include/version.h.
The firmware still reports

NodeMCU 2.2.0.0 build unspecified powered by Lua 5.1.4 on SDK 2.2.1(6ab97e9)

[nwf]

Bah humbug re: Espressif. We could leave it be or change user_version.h either to replace

#define NODE_VERSION_REVISION	ESP_SDK_VERSION_PATCH

with

#define NODE_VERSION_REVISION	1

or just bump NODE_VERSION_INTERNAL instead? I think I'd be more in favor of the last or the first, but this might just be bikeshedding.

[marcelstoer]

We could leave it [...]

In light of the discussions in #2398 I don't think we should.

P.S. -> espressif/ESP8266_NONOS_SDK#136

[nwf]

@marcelstoer How do you feel about calling this 2.2.0.1 while we wait on Espressif?

[marcelstoer]

@nwf I wouldn't do that. If Espressif fixes this we'd be shipping essentially the same SDK as before and, therefore, an change from 2.2.0.1 to 2.2.1.0 would feel odd to me.

[jmd13391]

Why don't we simply wait on SDK 2.2.1 until Espressif releases a fix?
Does anyone know if Espressif is aware of the issue?

[marcelstoer]

SDK 2.2.1 is already released, that's what this PR is about. See my comment further up.

[nwf]

@marcelstoer Admittedly, I was imagining we'd wait until 2.2.2 or 2.3.0 or 3.0.0 or whatever to re-merge with upstream, so we'd not do a 2.2.0.1 to 2.2.1.0 transition. I'm content to wait a bit to see what Espressif does.

[marcelstoer]

I'm content to wait a bit to see what Espressif does.

They haven't even commented on my PR in a month...