ndk-gdb testing

Setup steps

1. Sync the Android.mk samples with git clone -b android-mk https://github.com/googlesamples/android-ndk.git
2. Pick a sample app (e.g. Teapot), cd into its directory, and compile and install it to a device with android update project -p . --target <target> && ndk-build && ant clean debug install, where <target> is an SDK target such as android-23.
3. Run ndk-gdb.py. This can be done in three ways:
   1. Launch the application, and then run ndk-gdb from the app directory to attach the debugger.
   2. Run ndk-gdb --launch to have ndk-gdb start the application's main activity.
   3. Run ndk-gdb --launch-activity <activity name> to have ndk-gdb start a specific activity.
4. Test things!

Relevant things to test

1. Verify that backtraces are sensible.
2. Verify that breakpoints set before and after library load both work. (Using --launch vs. attaching after the application is running helps here.)
3. Verify that C++ stdlib pretty printers work (stlport and gnustl only).
4. Verify that ndk-gdb works with all valid combinations of app ABI support (defined in APP_ABI in Application.mk) and device ABI support. For example, test with the following combinations:
   1. 32-bit device:
      1. APP_ABI := armeabi
      2. APP_ABI := armeabi arm64-v8a
   2. 64-bit device:
      1. APP_ABI := armeabi
      2. APP_ABI := armeabi arm64-v8a
      3. APP_ABI := arm64-v8a