Build fix after issue #2284 fix.

samples/android/15-puzzle/src/org/opencv/samples/puzzle15/puzzle15Activity.java

@@ -58,7 +58,7 @@ public class puzzle15Activity extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/color-blob-detection/src/org/opencv/samples/colorblobdetect/ColorBlobDetectionActivity.java

@@ -53,7 +53,7 @@ public class ColorBlobDetectionActivity extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/face-detection/src/org/opencv/samples/fd/FdActivity.java

@@ -68,7 +68,7 @@ public class FdActivity extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/image-manipulations/src/org/opencv/samples/imagemanipulations/ImageManipulationsActivity.java

@@ -74,7 +74,7 @@ public class ImageManipulationsActivity extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/tutorial-1-addopencv/src/org/opencv/samples/tutorial1/Sample1Java.java

@@ -58,7 +58,7 @@ public class Sample1Java extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/tutorial-2-opencvcamera/src/org/opencv/samples/tutorial2/Sample2NativeCamera.java

@@ -64,7 +64,7 @@ public class Sample2NativeCamera extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/tutorial-3-native/src/org/opencv/samples/tutorial3/Sample3Native.java

@@ -55,7 +55,7 @@ public class Sample3Native extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();

samples/android/tutorial-4-mixed/src/org/opencv/samples/tutorial4/Sample4Mixed.java

@@ -63,7 +63,7 @@ public class Sample4Mixed extends Activity {
                     MarketErrorMessage.setCancelable(false); // This blocks the 'BACK' button
                     MarketErrorMessage.setButton(AlertDialog.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                         public void onClick(DialogInterface dialog, int which) {
-                            mAppContext.finish();
+                            finish();
                         }
                     });
                     MarketErrorMessage.show();