See if we can get vcpkg CI working again

.azure-pipelines/deployment-pipeline.yml

@@ -1,4 +1,4 @@
-# Copyright 2019 the Tectonic Project
+# Copyright 2019-2020 the Tectonic Project
 # Licensed under the MIT License.
 
 # Triggered when a deployment tag is pushed. This might be either the
@@ -47,7 +47,7 @@ jobs:
 
 - job: build_and_deploy_semistatic_macos
   pool:
-    vmImage: macOS-10.13  # vcpkg has a finicky build that currently requires this
+    vmImage: macOS-10.15
   steps:
   - template: set-deployment-variables-steps.yml
   - template: semistatic-macos-build-steps.yml

.azure-pipelines/pr-pipeline.yml

@@ -1,4 +1,4 @@
-# Copyright 2019 the Tectonic Project
+# Copyright 2019-2020 the Tectonic Project
 # Licensed under the MIT License.
 
 # This file defines a pipeline that runs upon pull requests to master. We do
@@ -38,6 +38,6 @@ jobs:
 
 - job: build_semistatic_macos
   pool:
-    vmImage: macOS-10.13  # vcpkg has a finicky build that currently requires this
+    vmImage: macOS-10.15
   steps:
   - template: semistatic-macos-build-steps.yml

.azure-pipelines/semistatic-macos-build-steps.yml

@@ -1,14 +1,11 @@
-# Copyright 2019 the Tectonic Project
+# Copyright 2019-2020 the Tectonic Project
 # Licensed under the MIT License.
 
 # Step to build and test the Tectonic binary in release mode on macOS using
 # vcpkg and static libraries for the system dependencies, resulting in a
 # binary that can run out-of-the-box on a macOS system.
 
-# vcpkg has a surprisingly finicky build. Right now the only way I can get it
-# to bootstrap is to use brew's gcc 9 on 10.13. Cf:
-# https://github.com/microsoft/vcpkg/issues/8627
-# https://github.com/microsoft/vcpkg/issues/7585
+# vcpkg has a surprisingly finicky build.
 
 steps:
 - script: |

.travis.yml

@@ -1,5 +1,5 @@
 # .travis.yml -- Travis CI specification file.
-# Copyright 2016-2019 the Tectonic Project
+# Copyright 2016-2020 the Tectonic Project
 # Licensed under the MIT License.
 
 language: rust
@@ -26,7 +26,7 @@ matrix:
       rust: nightly
     # MacOS, Rust stable: just a smoke test
     - os: osx
-      osx_image: xcode10.2
+      osx_image: xcode11.4
       rust: stable
   allow_failures:
     - rust: nightly