travis: add ppc64le and s390x builds

Closes #5752

.travis.yml

@@ -155,7 +155,7 @@ jobs:
         - libbrotli-dev
         - libzstd-dev
   - env:
-    - T=debug-mesalink C="--with-mesalink --without-ssl"
+    - T=debug-mesalink C="--with-mesalink --without-ssl" MESALINK=yes
     - OVERRIDE_CC="CC=gcc-8" OVERRIDE_CXX="CXX=g++-8"
     addons:
       apt:
@@ -349,6 +349,42 @@ jobs:
         - pkg-config
         - zlib1g-dev
 
+  - env:
+    - T=debug C="--enable-alt-svc"
+    - OVERRIDE_CC="CC=gcc-8" OVERRIDE_CXX="CXX=g++-8"
+    arch: ppc64le
+    addons:
+      apt:
+        <<: *common_apt
+        packages:
+        - *common_packages
+        - libpsl-dev
+        - libbrotli-dev
+        - libzstd-dev
+        - libev-dev
+        - libssl-dev
+        - libtool
+        - pkg-config
+        - zlib1g-dev
+
+  - env:
+    - T=debug C="--enable-alt-svc"
+    - OVERRIDE_CC="CC=gcc-8" OVERRIDE_CXX="CXX=g++-8"
+    arch: s390x
+    addons:
+      apt:
+        <<: *common_apt
+        packages:
+        - *common_packages
+        - libpsl-dev
+        - libbrotli-dev
+        - libzstd-dev
+        - libev-dev
+        - libssl-dev
+        - libtool
+        - pkg-config
+        - zlib1g-dev
+
 before_install:
 - export "${OVERRIDE_CC-blank=}"
 - export "${OVERRIDE_CXX-blank=}"

scripts/travis/before_script.sh

@@ -119,6 +119,7 @@ if [ $TRAVIS_OS_NAME = linux ]; then
   cd $HOME/wolfssl-4.4.0-stable
   sudo make install
 
+  if [ "$MESALINK" = "yes" ]; then
     if [ ! -e $HOME/mesalink-1.0.0/Makefile ]; then
       cd $HOME
       curl https://sh.rustup.rs -sSf | sh -s -- -y
@@ -130,10 +131,11 @@ if [ $TRAVIS_OS_NAME = linux ]; then
       ./configure --enable-tls13
       make
     fi
-
     cd $HOME/mesalink-1.0.0
     sudo make install
 
+  fi
+
   if [ ! -e $HOME/nghttp2-1.39.2/Makefile ]; then
     cd $HOME
     curl -LO https://github.com/nghttp2/nghttp2/releases/download/v1.39.2/nghttp2-1.39.2.tar.gz