execinfo.h is missing.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Currently the uwsgiconfig python script append some additional compilation flag based on the host system. This fix some problem related with this by hardcoding usgi_os variable to Linux

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

* Remove stray LICENSE file added to repo
* Use codeload instead of git
* Add proper (as close as possible) SPDX license
* Drop OpenSSL, PCRE and Libxml2 as dependencies
  Makes it more suitable alternative for small flash devices
* Drop /etc/uwsgi as there's only one config file
* Remove stray /etc/nginx directory
* Reorganize configuration file
* Convert init.d script to use procd
* Hardset 3 threads and processes, seems like a good tradeoff
  between performance and memory usage instead of doing
  auto scaling based on amout of cpu cores/threads

Non-scientific benchmark (tm)
ramips, mt7621, WiTi Board 16/256M

1. 3 threads, 6 processes
2. 2 threads, 2 processes
3. 3 threads, 3 processes

- LuCI Main page

1.48s
1.72s
1.64s

- Status --> Firewall

6.24s
6.39s
6.40s

- Status --> Kernel log

266ms
256ms
251ms

- Network --> Firewall

936ms
1.08s
1.07s

- Network --> Wireless

1.39s
1.42s
1.40s

Signed-off-by: Daniel Engberg <daniel.engberg.lists@pyret.net>