nginx: updated to 1.12.2

Changes with nginx 1.12.2:

*) Bugfix: client SSL connections were immediately closed if deferred
  accept and the "proxy_protocol" parameter of the "listen" directive
  were used.

*) Bugfix: client connections might be dropped during configuration
  testing when using the "reuseport" parameter of the "listen"
  directive on Linux.

*) Bugfix: incorrect response length was returned on 32-bit platforms
  when requesting more than 4 gigabytes with multiple ranges.

*) Bugfix: switching to the next upstream server in the stream module
  did not work when using the "ssl_preread" directive.

*) Bugfix: when using HTTP/2 client request body might be corrupted.

*) Bugfix: in handling of client addresses when using unix domain
  sockets.

(adam)