rtsp-client: RTP Info must exist in PLAY response

If RTP Info is missing. Then return GST_RTSP_STS_INTERNAL_SERVER_ERROR

Fixes #76
20 jobs for fix-rtp-info in 26 minutes and 20 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Preparation
passed #567234
gst indent

00:00:26

passed #567233
manifest

00:00:46

 
  Build
passed #567244
build cerbero android universal

00:15:08

passed #567245
build cerbero cross win32

00:15:16

passed #567246
build cerbero cross win64

00:10:22

passed #567243
build cerbero fedora x86_64

00:14:03

manual #567248
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #567247
gst-macos-10.14
build cerbero macos x86_64

00:16:41

passed #567239
build clang fedora x86_64

00:11:23

passed #567235
build fedora x86_64

00:05:23

passed #567242
docker windows 1607
build msys2

00:13:00

passed #567236
build nodebug fedora x86_64

00:11:59

passed #567237
build static fedora x86_64

00:20:45

passed #567238
build static nodebug fedora x86_64

00:11:54

passed #567240
docker windows 1607
build vs2017 amd64

00:10:04

passed #567241
docker windows 1607
build vs2017 x86

00:10:45

 
  Test
passed #567249
check fedora

00:04:33

passed #567250
integration testsuites fedora

00:20:08

 
  Integrate
passed #567251
android universal examples

00:07:34

passed #567252
documentation

00:05:00