The adress of struct sock, which are used as the map key, are often
reused. When it happens random duration appears in the MS field for
new connections (CLOSE->SYN_SENT and LISTEN->SYN_RECV
transitions). Let's forget about the socket when the connection is
closed.

It is recommended to use bpf_probe_read_kernel_{str} in the bpf tools.
See kernel commit 0ebeea8ca8a4 ("bpf: Restrict bpf_probe_read{, str}()
only to archs where they work")

Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>

The tracepoint inet_sock_set_state only exists in kernels 4.15.
Backported the bpf tracepoint to use kprobes on older kernels.

fix a bunch of types in man pages, docs, tools, tests, src and examples.

Simplify code following #2198 (https://github.com/iovisor/bcc/pull/2198).

Some tools are not touched: mountsnoop.py, trace.py, lib/*.py, old/*.py.

* fixed shebangs in tools (and lib)

* fixed shebangs in examples

* do not mangle shebangs in rpm spec

* renamed style-check.sh to c-style-check.sh

* factored out python linter to a separate file

* added shebang validation to the py-style-check

* added shebangs to all python executables

Many tools rely on the user to type Ctrl-C to end, but don't actually
catch the keyboard interrupt and thus show an ugly backtrace when it
happens. Let's catch the interrupt.

* tcpstates: Add systemd journal logging.

Add a -Y/--journal flag to tcpstates.py, which logs events to the
systemd journal.

* tcpstates: Document systemd journal logging.

Update tcpstates_example.txt and tcpstates.8 to include the "-Y" flag.

* tools: uses 'replace' error handler by default in decode()

Tools might encouter characters from non utf-8 charset (e.g. a file
name). When this happen, it's better to replace the unexpected
character by a question mark than crash the tool when all we do is
to print the string.

* tools: fix a bytes/string issue in attach_perf_event()

Finish the conversion started with commit 36ce1124.

Minor tweaks to make the tools consistent within themselves.

make types appropriate for ipaddr/protocol etc.