reason: some target call python3 to generate some headers,
if PYTHON_EXECUTABLE changed, headers will be invalid, which
will lead to rebuild most of obj, because this headers will
be include in most cpp/c, what`s more, this target do not depends
python3 version(python API) the output is same when use python3.5
or python3.x so change use PYTHON_EXECUTABLE to
PYTHON3_EXECUTABLE_WITHOUT_VERSION, when
PYTHON_EXECUTABLE/PYTHON_LIBRARY/PYTHON_INCLUDE_DIR changed,
can reuse the build obj

GitOrigin-RevId: c2ffe3ead3a295377a691587ab097636562f571e