If the `fun F/A` syntax is used multiple times with the same `F/A`,
(for examle, `fun foo/2`), there would a wrapper function and fun
entry generated for each occurrence.

Using the new support in the OTP 23 runtime system, generate a single
wrapper function and fun entry for each `F/A`. Since there is only one
wrapper function, it can be named based on the name of the function it
calls to faciliate debugging, not based on the function that defines
the fun. For example, the wrapper function for `fun foo/0` will now be
named `-fun.foo/0-'.

* john/tools/fix-cover-register-race/ERL-943/OTP-15813:
  cover: Fix register/2 race on startup

* dgud/emacs-test-uc-path:
  Fix emacs tests

* lukas/tools/overhead_benchmark:
  etp: Fix free de processes check
  tools: Add overhead benchmark

Didn't work if installed path contained spaces or unicode characters.

Fetch and present arity in the *xref* window (unless too many hits).

If we are reasonably sure which definition the user wants to go to
then jump there directly instead of popping to the *xref* window.

Use `counters:add/3` instead of `ets:update_counter/3`
for counting the number of times a line is executed.

By default, the reference to the counter array for each module will be
stored in a persistent term and retrieved every time a counter is
updated. This makes the compiler test suite with coverage enabled run
*almost* twice as fast (on my computer, in about 6 minutes down from
more than 11 minutes).

To get even more speed, the new `cover:local_only/0` function can be
called to put cover into a mode where the cover-compiled code can only
be run on the local node. In this mode, the cover-compiled modules in
a more efficient way by compiling the counter reference into the
code. This shaves off about one more minute, making the compiler test
suite with coverage enabled run *more than* twice as fast (in about 5
minutes on my computer).