rtmpdump: Switch to git:// as https:// seems broken

Author: wader

Dockerfile

@@ -541,7 +541,7 @@ RUN \
 # bump: librtmp /LIBRTMP_COMMIT=([[:xdigit:]]+)/ gitrefs:https://git.ffmpeg.org/rtmpdump.git|re:#^refs/heads/master$#|@commit
 # bump: librtmp after ./hashupdate Dockerfile LIBRTMP $LATEST
 # bump: librtmp link "Commit diff $CURRENT..$LATEST" https://git.ffmpeg.org/gitweb/rtmpdump.git/commitdiff/$LATEST?ds=sidebyside
-ARG LIBRTMP_URL="https://git.ffmpeg.org/rtmpdump.git"
+ARG LIBRTMP_URL="git://git.ffmpeg.org/rtmpdump.git"
 ARG LIBRTMP_COMMIT=138fdb258d9fc26f1843fd1b891180416c9dc575
 RUN \
   git clone "$LIBRTMP_URL" && cd rtmpdump && \