fix ndk download

Author: abaker

.github/workflows/build.yml

@@ -144,8 +144,10 @@ jobs:
           java-version: '11'
 
       - name: Install pinned Android NDK
-        run: |
-          echo y | $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager "ndk;21.3.6528147"
+        # sdkmanager on current runner images requires JDK 17+, but Gradle 6.1.1
+        # (AGP 4.0) tops out below that. Use the runner's pre-installed JDK 17
+        # just for this step; subsequent steps stay on JDK 11 for Gradle.
+        run: echo y | JAVA_HOME="$JAVA_HOME_17_X64" $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager "ndk;21.3.6528147"
 
       - name: Download native libs
         uses: actions/download-artifact@v4