Update Ubuntu version on Azure

The i386 and community jobs were still on 16.04, update them to
18.04.

Author: nikic

azure/community_job.yml

@@ -16,7 +16,7 @@ jobs:
   - job: ${{ parameters.configurationName }}
     timeoutInMinutes: ${{ parameters.timeoutInMinutes }}
     pool:
-      vmImage: 'ubuntu-16.04'
+      vmImage: 'ubuntu-18.04'
     variables:
       ubsan_options: 'print_stacktrace=1'
     steps:

azure/i386/apt.yml

@@ -13,7 +13,7 @@ steps:
                               locales \
                               language-pack-de \
                               libglib2.0-dev:i386 \
-                              openssl:i386 \
+                              libssl-dev:i386 \
                               zlib1g-dev:i386 \
                               libxml2-dev:i386 \
                               libgmp-dev:i386 \

azure/i386/job.yml

@@ -5,7 +5,7 @@ parameters:
 jobs:
   - job: ${{ parameters.configurationName }}
     pool:
-      vmImage: 'ubuntu-16.04'
+      vmImage: 'ubuntu-18.04'
     steps:
     - template: apt.yml
     - script: |