fix mat_pixel_android.cpp shadowed variables warning (#2447)

src/mat_pixel_android.cpp

@@ -186,17 +186,14 @@ void Mat::to_android_bitmap(JNIEnv* env, jobject bitmap, int type_from) const
     AndroidBitmap_getInfo(env, bitmap, &info);
 
     int type_to;
-    int elempack;
 
     if (info.format == ANDROID_BITMAP_FORMAT_A_8)
     {
         type_to = PIXEL_GRAY;
-        elempack = 1;
     }
     else if (info.format == ANDROID_BITMAP_FORMAT_RGBA_8888)
     {
         type_to = PIXEL_RGBA;
-        elempack = 4;
     }
     else
     {
@@ -207,12 +204,12 @@ void Mat::to_android_bitmap(JNIEnv* env, jobject bitmap, int type_from) const
     // let PIXEL_XXX2RGBA become PIXEL_XXX
     type_from = (type_from & PIXEL_CONVERT_MASK) ? (type_from & PIXEL_FORMAT_MASK) : type_from;
 
-    void* data;
-    AndroidBitmap_lockPixels(env, bitmap, &data);
+    void* _data;
+    AndroidBitmap_lockPixels(env, bitmap, &_data);
 
     int type = type_from == type_to ? type_to : (type_from | (type_to << PIXEL_CONVERT_SHIFT));
 
-    to_pixels_resize((unsigned char*)data, type, info.width, info.height, info.stride);
+    to_pixels_resize((unsigned char*)_data, type, info.width, info.height, info.stride);
 
     AndroidBitmap_unlockPixels(env, bitmap);
 }