THRIFT-4308: re-enable dlang deimos build support for libevent
and openssl, working around a dmd link order issue.
Update dotnet-sdk to 2.1.4 (was 2.0.5) because of build failures

Client: d
Client: netcore

This closes #1483
diff --git a/build/docker/ubuntu-trusty/Dockerfile b/build/docker/ubuntu-trusty/Dockerfile
index 5d7cec2..40f9c55 100644
--- a/build/docker/ubuntu-trusty/Dockerfile
+++ b/build/docker/ubuntu-trusty/Dockerfile
@@ -86,15 +86,15 @@
       dfmt \
       dscanner \
       xdg-utils
-# RUN mkdir -p /usr/include/dmd/druntime/import/deimos /usr/include/dmd/druntime/import/C && \
-#     curl -sSL https://github.com/D-Programming-Deimos/libevent/archive/master.tar.gz| tar xz && \
-#     mv libevent-master/deimos/* /usr/include/dmd/druntime/import/deimos/ && \
-#     mv libevent-master/C/* /usr/include/dmd/druntime/import/C/ && \
-#     rm -rf libevent-master
-# RUN curl -sSL https://github.com/D-Programming-Deimos/openssl/archive/master.tar.gz| tar xz && \
-#     mv openssl-master/deimos/* /usr/include/dmd/druntime/import/deimos/ && \
-#     mv openssl-master/C/* /usr/include/dmd/druntime/import/C/ && \
-#     rm -rf openssl-master
+RUN mkdir -p /usr/include/dmd/druntime/import/deimos /usr/include/dmd/druntime/import/C && \
+    curl -sSL https://github.com/D-Programming-Deimos/libevent/archive/master.tar.gz| tar xz && \
+    mv libevent-master/deimos/* /usr/include/dmd/druntime/import/deimos/ && \
+    mv libevent-master/C/* /usr/include/dmd/druntime/import/C/ && \
+    rm -rf libevent-master
+RUN curl -sSL https://github.com/D-Programming-Deimos/openssl/archive/master.tar.gz| tar xz && \
+    mv openssl-master/deimos/* /usr/include/dmd/druntime/import/deimos/ && \
+    mv openssl-master/C/* /usr/include/dmd/druntime/import/C/ && \
+    rm -rf openssl-master
 
 RUN apt-get install -y --no-install-recommends \
 `# Dart dependencies` \