Add 32-bit Linux build to CI

azure-pipelines.yml

@@ -100,6 +100,18 @@ jobs:
       buildPlatform: AppImage
   dependsOn: Linux
   condition: succeeded()
+- job: Linux32
+  pool:
+    vmImage: ubuntu-16.04
+  steps:
+  - script: azure-pipelines/build-linux32
+    displayName: 'Linux 32-bit'
+  - task: PublishTestResults@2
+    inputs:
+      testRunTitle: Linux32
+      buildPlatform: Linux32
+  dependsOn: Linux
+  condition: succeeded()
 - job: Fuzzers
   pool:
     vmImage: ubuntu-16.04

azure-pipelines/build-linux32

@@ -0,0 +1,24 @@
+#!/bin/bash
+set -ex
+
+# dpkg --add-architecture not needed for Ubuntu 18.04
+sudo dpkg --add-architecture i386
+
+sudo apt-get update
+
+# For Ubuntu 18.04:
+#
+# sudo apt-get -y install \
+#    autoconf build-essential zlib1g-dev:i386 libjpeg-dev:i386 \
+#    g++-multilib-i686-linux-gnu
+# ./configure --enable-werror --enable-show-failed-test-output \
+#     CC=i686-linux-gnu-gcc CXX=i686-linux-gnu-g++
+
+sudo apt-get -y install \
+   autoconf build-essential zlib1g-dev:i386 libjpeg-dev:i386 \
+   g++-multilib
+./configure --enable-werror --enable-show-failed-test-output \
+    CFLAGS=-m32 CXXFLAGS=-m32 LDFLAGS=-m32
+
+make -j$(nproc) -k
+make -k check