I have been using 11.4.0 for some time. All was fine.
I downloaded 11.5, extracted, run ./configure, make, make install. I got a message about res_rtp_asterisk.so was not compiled in the 11.5
Sure enough I have rss_rtp_asterisk.c but not .o file and no .so file.
I then looked in the config.log and nothing is in there about res_rtp_asterisk