Use NDK r21e (installed by prereqs script) for Android builds. (#986)

* Use NDK r21e (installed by prereqs script) for Android builds.

Author: jonsimantov

.github/workflows/android.yml

@@ -126,6 +126,8 @@ jobs:
         shell: bash
         run: |
           build_scripts/android/install_prereqs.sh
+          echo "NDK_ROOT=/tmp/android-ndk-r21e" >> $GITHUB_ENV
+          echo "ANDROID_NDK_HOME=/tmp/android-ndk-r21e" >> $GITHUB_ENV
 
       - name: Add strings.exe to PATH (Windows only)
         if: startsWith(matrix.os, 'windows')

.github/workflows/integration_tests.yml

@@ -509,6 +509,8 @@ jobs:
           shell: bash
           command: |
             build_scripts/android/install_prereqs.sh
+            echo "NDK_ROOT=/tmp/android-ndk-r21e" >> $GITHUB_ENV
+            echo "ANDROID_NDK_HOME=/tmp/android-ndk-r21e" >> $GITHUB_ENV
             pip install -r scripts/gha/requirements.txt
             python scripts/gha/restore_secrets.py --passphrase "${{ secrets.TEST_SECRET }}"
       - name: Fetch prebuilt packaged SDK from previous run