make_impala.sh seems to be an unnecessary layer in the build system between buildall.sh and the CMake scripts. Per discussion on dev@, I think we should:
- Move any logic required for doing incremental builds into CMakeLists. E.g. gen_build_version.py
- maybe consider moving the CMake invocation logic into a separate script that does one clear-cut thing
- Move the make invocation logic into a function in buildall.sh
- Add support to buildall.sh to build both the debug and release binaries.