Provide a sample app for the BakeBread tool

[paul-mc-arrow]

Instead of coding a fresh sample app, I decided to build on top of the sample app you are familiar with.
To build, I followed the outlines at
https://support.hockeyapp.net/kb/client-integration-android/hockeyapp-for-android-ndk-early-access
https://chromium.googlesource.com/breakpad/breakpad/+/master/README.md

To illustrate the capabilities of postmortem debugging, I replaced the simple "null dereference" crash with two more sophisticated examples: pointer sort based on a custom comparator. Variables in the "stack" example can be read from the kind of dump Breakpad creates by default: thread stacks, memory maps and a tiny tip of code around the instruction pointer. The "heap"/"off-stack" example demonstrates a flaw in an STL container. To debug it, we need the "sweet cuts" of the heap.

To separate the wrapper code from the purposefully faulty sample code, the former has been placed in breakpad.cpp and the latter in crash.cpp.
native.cpp stayed the only C++ source file aware of JNI types.