patch 8.1.1507: sound test still fails on Travis

Problem:    Sound test still fails on Travis.
Solution:   Try another dummy sound approach.

.travis.yml

@@ -121,25 +121,16 @@ before_install:
     if [[ "${TRAVIS_OS_NAME}" = "linux" ]] && [[ "${CC}" = "clang" ]]; then
       ln -sf "$(which llvm-cov)" /home/travis/bin/gcov
     fi
-  # Should make sound work (might not all be needed)
-  - |
-    if [[ "${TRAVIS_OS_NAME}" = "linux" ]]; then
-      sudo apt-get update -qq
-      sudo usermod -a -G audio travis
-      sudo apt-get install -y portaudio19-dev
-      sudo apt-get install -y libasound2-dev alsa-utils alsa-oss
-      sudo bash test/prep-dummy-soundcard.sh
-      sudo apt-get install -y lame
-    fi
 
 before_script:
   # Start virtual framebuffer to be able to test the GUI. Does not work on OS X.
+  # Install dummy device for sound.
   - |
     if [[ "${TRAVIS_OS_NAME}" = "linux" ]]; then
       export DISPLAY=:99.0
       sh -e /etc/init.d/xvfb start && sleep 3
-      # pretend to play sound
-      export AUDIODEV=null
+      sudo modprobe snd-dummy
+      sudo usermod -a -G audio $USER
     fi
 
 script:

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1507,
 /**/
     1506,
 /**/