Revision history for port from OpenBSD tcpbench to GNU/Linux.

2.00 2023-05-22
    - Remove many #ifdef OpenBSD as kvm PCB table was replaced with
      getsockopt(TCP_INFO) which also exists on Linux.
    - Update to OpenBSD tcpbench.c revision 1.69.
    - Respect environment CFLAGS, CPPFLAGS and LDFLAGS in GNU
      makefile.

1.01 2022-08-08
    - Link with libevent2 instead of libev on GNU/Linux.
    - Fix build on Ubuntu.

1.00 2022-08-07
    - Initial public release based on OpenBSD tcpbench.c 1.59.
