A separate build_id stackmap can be created with the help of new macro BPF_STACK_TRACE_BUILDID. The kernel BPF reports stacktrace in the 
structure bpf_stack_build_id. Changes have been made to BPF modules to
support resolving symbols mentioned in the above format.
An example tool is also available in examples/tracing/stack_buildid_example.py. 
Both python and C++ test cases are added.