Unfortunately some Red Hat-based distributions lack the required header.
See https://bugzilla.redhat.com/show_bug.cgi?id=815587

This reverts commit 261a389a.
This reverts commit b6736eb0.

Fixes #233 github issue.

This removes our direct zlib dependency (although of course protobuf
still uses it internally), removes a fixed 4 MiB buffer and its
corresponding limit on the terminal size, reduces some string copying,
and deletes some code.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

(Closes #230.)

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

Pull in third-party poll emulator and automatically link it in if we detect the system's poll is broken

Also increases maximum frame rate from 50 fps to 100 fps.

Relevant to issue #222 on github.

Closes #6

Closes #225 github issue (Jay Freeman).

Relevant to #217.

Otherwise that variable has no effect.

Suggested by Kees Cook.

Through Autoconf we set hardening flags that are actually more aggressive than
the Ubuntu defaults, but they conflict with same.

Closes #196.