Add systemd socket activation for epmd.

Check for systemd libraries and headers in confgiure.
Add -systemd option enabling waiting for sockets from systemd.
Remove a superfluous echo in the emulator Makefile

It pollutes the output of silent rules.
test_server: Allow init_per_ function to throw skip

Allow all init_per_[suite|group|testcase] to throw (or exit)
{skip, Reason} to explicitly ignore tests without failing.

It is easier to catch it in one place instead of writing a try
in each init_per_* to return {skip, Reason}.
Pass full strings to DTrace probes

Whenever string is passed as an argument to a DTrace probe, its length
should be properly computed. Until now in order to get length of the
input buffer size_of(char *) was used - which evalutes to 4 or 8
(depending on the architecture). To get a proper length,
size_of(DTRACE_CHARBUF_NAME(buffer_name)) should be used.
[snmp/agent] Fixed the loop_mib test cases
[snmp/agent] Fixed request id generation

When testing the agent, it is started and then used for a series
(v1, v2, v3, ...) of tests. But the individual test cases are
use one instance of the test manager. Because of this, the requerst
id cannot be a counter starting from 1 or any counter for that
matter. Instead every request id was generated using random.
But this is obiously not a guarantee fo uniqueness, it merely
makes it unlikely that the request ids will be reused.
To get around this problem (without having to rewrite the
entire agent test suite) a simple (global) counter server is
introduced. It is started at the start of the agent test suite
(init_per_suite) and stopped at the end (end_per_suite).
[snmp/manager] Verify success for app start and stop in test cases

When starting and stopping apps verify success. If failure
to start or stop app force failure of test case or init/fin
of test case. Also, be more verbose regarding stop results
during test case finish.
[snmp/agent] CLeanup - unused vars and use of deprecated funcs
Remove RTL code that handled the (is_)constant guard

The (is_)constant/1 guard is removed from Erlang long ago and thus
there is no need to handle it in RTL.

While editing these files, also performed some minor cleanup.
Shorten default timetrap timeout for ct_master test suite
wx: Fix configure for win64 with wxWidgets-3.0
wx: Fix listCtrl sort callback
[snmp/manager] Add some more error handling when starting

Add some more error handling (a try catch block) when starting
both manager and agent.
eldap: Fix asn.1 decode into binaries
fix sys:get_state/1,2 and sys:replace_state/2,3 when sys suspended

Add two new system callbacks Module:system_get_state/1 and
Module:system_replace_state/2 to allow sys:get_state/1,2 and
sys:replace_state/2,3 to operate correctly even if a process is sys
suspended. Modify gen_server, gen_fsm, and gen_event to support the new
callbacks.

If a callback module does not export these functions, then by default the
Misc value (the same as that passed as the final argument to
sys:handle_system_msg/6, and returned as part of the return value of
sys:get_status/1,2) is treated as the callback module's state.

The previous behaviour of intercepting the system message and passing a
tuple of size 2 as the last argument to sys:handle_system_msg/6 is no
longer supported.

Add tests to verify the correctness of sys:get_state/1,2 and
sys:replace_state/2,3 when processes are sys suspended. Add two tests for
modules that implement special processes, one that exports
system_get_state/1 and system_replace_state/2 and one that doesn't.

Much of the credit for this patch goes to James Fish, who reported the
initial problem and implemented much of the fix.
remove tuple funs from special process documentation

Support for tuple funs was removed in R16B but the documentation for
special processes, sys, and proc_lib in the OTP Design Principles still
showed examples using them, and those examples no longer worked. Fix the
examples to use regular functions instead and fix the documentation to
reflect the changes.
Fix some dialyzer warnings in ct_netconfc
inets: Remove potential windows problem
Change release name from "OTP APN 181 01" to "Erlang/OTP"
Update primary bootstrap

   bootstrap/bin/start.boot
   bootstrap/bin/start_clean.boot