SDP is obsolete

[bsmith94]

I cannot find an official announcement, but it looks like SDP has been deprecated/obsolete for quite some time. It seems like sdp_bw and sdp_lat should be removed from qperf's set of tests.

The current behavior (debian 8, kernel 3.16.0-4, libsdp-1.1.99-2.1) is that qperf reports:

# LD_PRELOAD=libsdp.so qperf
unable to bind to listen port

/tmp/libsdp.1000.log:

Thu Nov 16 23:20:06 2017 qperf[2287] libsdp Error socket: <97> calling socket for SDP socket

97 == EAFNOSUPPORT returned from the call to socket(AF_INET_SDP...).

For the sake of identifying prior art: RHEL's qperf-0.4.9-3.el7.src.rpm has a patch that removes the sdp tests from src/help.txt, although it does not remove the tests from the source code.

Likely paths toward resolution appear to be:

1. Remove qperf's SDP features.
2. Make qperf's SDP features optional, via configure, with a default of disabled.
3. Improve the error message to inform the user that SDP is not supported by the OS.
4. 2 and 3.

Thoughts?