Introduce CodeQL analysis

While there, tweak some indentation in another GitHub Actions workflow
file.

.github/workflows/build.yaml

@@ -29,11 +29,11 @@ jobs:
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.experimental }}
     steps:
-        # We run the build twice for each supported JDK: once against the
-        # original Error Prone release, using only Error Prone checks available
-        # on Maven Central, and once against the Picnic Error Prone fork,
-        # additionally enabling all checks defined in this project and any
-        # Error Prone checks available only from other artifact repositories.
+      # We run the build twice for each supported JDK: once against the
+      # original Error Prone release, using only Error Prone checks available
+      # on Maven Central, and once against the Picnic Error Prone fork,
+      # additionally enabling all checks defined in this project and any Error
+      # Prone checks available only from other artifact repositories.
       - name: Check out code
         uses: actions/[email protected]
       - name: Set up JDK

.github/workflows/codeql.yml

@@ -0,0 +1,41 @@
+name: CodeQL
+on:
+  pull_request:
+    branches: [ master ]
+  push:
+    branches: [ master ]
+  schedule:
+    - cron: '0 4 * * 1'
+permissions:
+  actions: read
+  contents: read
+  security-events: write
+jobs:
+  analyze:
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ java, ruby ]
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Check out code
+        uses: actions/[email protected]
+      - name: Initialize CodeQL
+        uses: github/codeql-action/[email protected]
+        with:
+          languages: ${{ matrix.language }}
+      # XXX: Check whether we should do this instead.
+      #- name: Set up JDK
+      #  uses: actions/[email protected]
+      #  with:
+      #    java-version: 17.0.6
+      #    distribution: temurin
+      #    cache: maven
+      #- name: Perform minimal build
+      #  run: mvn -T1C clean install -DskipTests -Dverification.skip 
+      - name: Perform autobuild
+        uses: github/codeql-action/[email protected]
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/[email protected]
+        with:
+          category: "/language:${{matrix.language}}"