CI: add dmd support

[Akim Demaille]

commit dbb855895fbafe5226b3ac607eee4b22837c7ff7
Author: Eduard Staniloiu <address@hidden>
Date:   Mon Dec 10 15:18:37 2018 +0200

    CI: add dmd support
    
    * .travis.yml: here.

diff --git a/.travis.yml b/.travis.yml
index 0a183300..5a1ca282 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -311,11 +311,15 @@ before_install:
   - sudo apt-get install -qq autoconf automake autopoint doxygen flex gettext 
graphviz help2man m4 texinfo
   - if [[ $CC == "icc" ]]; then build-aux/install-icc.sh; fi
   - if [[ -f ~/.bashrc ]]; then source ~/.bashrc; fi
+  # Install and activate dmd
+  - mkdir -p ~/dlang && wget https://dlang.org/install.sh -O ~/dlang/install.sh
+  - source $(source ~/dlang/install.sh dmd -a)
   - autoconf --version
   - automake --version
   - autopoint --version
   - $CC --version
   - $CXX --version
+  - dmd --version
   - doxygen --version
   - flex --version
   - gettext --version