[PATCH, RFC v3 0/3] add xtensa port

[Alexey Lapshin]

Hi Jeff,

Yes, https://github.com/espressif/newlib-esp32 is a project files come from.

Espressif toolchain will be released soon, and this repo will receive a new branch that updates copyright headers, similar to the sent patches

sim-vectors.S is a modifyed version of this file: https://github.com/espressif/esp-idf/blob/master/components/xtensa/xtensa_vectors.S

Regards,
Alexey