Disable NDK downloading for Travis CI build

NDK is multi-platform, so natives can be updated by developer.

.travis.yml

@@ -8,10 +8,10 @@ branches:
 
 before_install:
   # required libs for android build tools
-  - sudo apt-get update
-  - sudo apt-get install -qq p7zip-full
+  # sudo apt-get update
+  # sudo apt-get install -qq p7zip-full
   # sudo apt-get install -qq --force-yes libgd2-xpm ia32-libs ia32-libs-multiarch
   # newest Android NDK
-  - wget http://dl.google.com/android/ndk/android-ndk-r10c-linux-x86_64.bin -O ndk.bin
-  - 7z x ndk.bin -y > /dev/null
-  - export ANDROID_NDK=`pwd`/android-ndk-r10c
+  # wget http://dl.google.com/android/ndk/android-ndk-r10c-linux-x86_64.bin -O ndk.bin
+  # 7z x ndk.bin -y > /dev/null
+  # export ANDROID_NDK=`pwd`/android-ndk-r10c