IssueTracker

This doesn't repro for me. Steps:
(1) Create new C++ project
(2) Run the app (this create's the binary directories
(3) Do something to cause a gradle Sync
(4) Look for files under .externalNativeBuild. They're there:
    jomof@jomof:~/projects/client/src/android/MyApplication4/app$ find "." -name "*.o"
    ./.externalNativeBuild/cmake/debug/x86/CMakeFiles/native-lib.dir/src/main/cpp/native-lib.cpp.o

Please add repro steps so I can get a better idea of what's happening.

>>  It should only delete the CMake binary directories *if and only if* parameters change in Gradle that cause cmake toolchain parameters to change (such as platform version, abi, toolchain) or parameters passed to CMake to change.
This is the way it's design to work and it is working that way for the cases I know

I realized that there were a few things we were doing that were questionable. Specifically, we set up our CMake command line params in a variable at the root build.gradle script. We were generating build dates and such in gradle and passing those down to CMake. I think things like this may be causing the CMake args to change too often, possibly resulting in this behavior. I'm in the process of eliminating a lot of this, so I'll make sure to report back the results.