Set up CI with Azure Pipelines (#275)

ci/azure-cross-compile.yml

@@ -0,0 +1,55 @@
+parameters:
+  cmd: test
+  rust_version: stable
+
+jobs:
+- job: ${{ parameters.name }}
+  displayName: Cross
+  strategy:
+    matrix:
+      i686:
+        vmImage: ubuntu-16.04
+        target: i686-unknown-linux-gnu
+      armv7:
+        vmImage: ubuntu-16.04
+        target: armv7-unknown-linux-gnueabihf
+      powerpc:
+        vmImage: ubuntu-16.04
+        target: powerpc-unknown-linux-gnu
+      powerpc64:
+        vmImage: ubuntu-16.04
+        target: powerpc64-unknown-linux-gnu
+      wasm:
+        vmImage: ubuntu-16.04
+        target: wasm32-unknown-unknown
+  pool:
+    vmImage: $(vmImage)
+
+  steps:
+    - template: azure-install-rust.yml
+      parameters:
+        rust_version: ${{parameters.rust_version}}
+
+    # FIXME(taiki-e): When https://github.com/rust-embedded/cross/pull/169 is
+    # merged, switch to the installation from crates.io.
+    # See https://nbsoftsolutions.com/blog/azure-pipelines-for-rust-projects#workaround-cross-compilation
+    # for the current script.
+    - script: |
+        git clone https://github.com/rust-embedded/cross.git
+        cd cross
+        git apply ../ci/cross-patch
+        cargo install --path .
+        rm -rf cross
+      displayName: Install cross
+      condition: not(eq(variables['target'], 'wasm32-unknown-unknown'))
+
+    - script: cross ${{ parameters.cmd }} --target $(target)
+      displayName: cross ${{ parameters.cmd }} --target $(target)
+      condition: not(eq(variables['target'], 'wasm32-unknown-unknown'))
+
+    # WASM support
+    - script: |
+        rustup target add $(target)
+        cargo build --target $(target)
+      displayName: cargo build --target $(target)
+      condition: eq(variables['target'], 'wasm32-unknown-unknown')