CI: add build with ngtcp2 + gnutls on Travis CI

.travis.yml

@@ -150,6 +150,30 @@ matrix:
                       - *common_packages
                       - libpsl-dev
                       - libbrotli-dev
+        - os: linux
+          compiler: gcc
+          dist: xenial
+          env:
+              - T=novalgrind NGTCP2=yes GNUTLS=yes C="PKG_CONFIG_PATH=$HOME/ngbuild --without-ssl --with-gnutls=$HOME/ngbuild --with-ngtcp2=$HOME/ngbuild --with-nghttp3=$HOME/ngbuild --enable-alt-svc" NOTESTS=
+              - OVERRIDE_CC="CC=gcc-8" OVERRIDE_CXX="CXX=g++-8"
+          addons:
+              apt:
+                  sources:
+                      - *common_sources
+                  packages:
+                      - *common_packages
+                      - libpsl-dev
+                      - libbrotli-dev
+                      - autogen
+                      - automake
+                      - autopoint
+                      - bison
+                      - gperf
+                      - libgmp-dev
+                      - libopts25-dev
+                      - libp11-kit-dev
+                      - libtasn1-6-dev
+                      - nettle-dev
         - os: linux
           compiler: gcc
           dist: bionic

scripts/travis/before_script.sh

@@ -25,12 +25,30 @@ set -eo pipefail
 ./buildconf
 
 if [ "$NGTCP2" = yes ]; then
-  cd $HOME
-  git clone --depth 1 -b OpenSSL_1_1_1d-quic-draft-27 https://github.com/tatsuhiro-t/openssl possl
-  cd possl
-  ./config enable-tls1_3 --prefix=$HOME/ngbuild
-  make
-  make install_sw
+  if [ "$TRAVIS_OS_NAME" = linux -a "$GNUTLS" ]; then
+    cd $HOME
+    git clone --depth 1 https://gitlab.com/gnutls/nettle.git
+    cd nettle
+    ./.bootstrap
+    ./configure LDFLAGS="-Wl,-rpath,$HOME/ngbuild/lib" --disable-documentation --prefix=$HOME/ngbuild
+    make
+    make install
+
+    cd $HOME
+    git clone --depth 1 -b tmp-quic https://gitlab.com/gnutls/gnutls.git pgtls
+    cd pgtls
+    ./bootstrap
+    ./configure PKG_CONFIG_PATH=$HOME/ngbuild/lib/pkgconfig LDFLAGS="-Wl,-rpath,$HOME/ngbuild/lib" --with-included-libtasn1 --with-included-unistring --disable-guile --disable-doc --prefix=$HOME/ngbuild
+    make
+    make install
+  else
+    cd $HOME
+    git clone --depth 1 -b OpenSSL_1_1_1d-quic-draft-27 https://github.com/tatsuhiro-t/openssl possl
+    cd possl
+    ./config enable-tls1_3 --prefix=$HOME/ngbuild
+    make
+    make install_sw
+  fi
 
   cd $HOME
   git clone --depth 1 https://github.com/ngtcp2/nghttp3