android: update build_sdk.py

- configuration files for ABIs configuration
- use builtin Android NDK's toolchain by default (force flag to use OpenCV's toolchain)
- default values for 'work_dir' and 'opencv_dir'

platforms/android/ndk-10.config.py

+ABIs = [
+    ABI("2", "armeabi-v7a", "arm-linux-androideabi-4.8", cmake_vars=dict(ANDROID_ABI='armeabi-v7a with NEON')),
+    ABI("1", "armeabi",     "arm-linux-androideabi-4.8"),
+    ABI("3", "arm64-v8a",   "aarch64-linux-android-4.9"),
+    ABI("5", "x86_64",      "x86_64-4.9"),
+    ABI("4", "x86",         "x86-4.8"),
+    ABI("7", "mips64",      "mips64el-linux-android-4.9"),
+    ABI("6", "mips",        "mipsel-linux-android-4.8")
+]

platforms/android/ndk-16.config.py

+ABIs = [
+    ABI("2", "armeabi-v7a", "arm-linux-androideabi-4.9", cmake_vars=dict(ANDROID_ABI='armeabi-v7a with NEON')),
+    ABI("1", "armeabi",     "arm-linux-androideabi-4.9", cmake_vars=dict(WITH_TBB='OFF')),
+    ABI("3", "arm64-v8a",   "aarch64-linux-android-4.9"),
+    ABI("5", "x86_64",      "x86_64-4.9"),
+    ABI("4", "x86",         "x86-4.9"),
+]

platforms/android/service/engine/src/org/opencv/engine/OpenCVEngineService.java

@@ -119,9 +119,12 @@ public class OpenCVEngineService extends Service {
 
             @Override
             public String getLibraryList(String version) throws RemoteException {
-                for (LibVariant lib : variants)
+                Log.i(TAG, "getLibraryList(" + version + ")");
+                for (LibVariant lib : variants) {
+                    Log.i(TAG, "checking " + lib.version + " ...");
                     if (lib.isCompatible(version))
                         return lib.getFileList();
+                }
                 return null;
             }