Disable accidentally enabled floating point exceptions on MacOS X

In c7ddafbe, which disabled floating point exceptions on Linux,
floating point exceptions were accidentally enabled on MacOS X.
Let xcomp/README.md refer to HOWTO/INSTALL-CROSS.md
Update preloaded and primary bootstrap
Merge branch 'bjorn/erts/fp-exceptions-on-osx'

* bjorn/erts/fp-exceptions-on-osx:
  Disable accidentally enabled floating point exceptions on MacOS X
Merge branch 'rickard/xcomp-readme'

* rickard/xcomp-readme:
  Let xcomp/README.md refer to HOWTO/INSTALL-CROSS.md
erts: Fix Map cmp exact equal of an empty map

The expression,

  #{} =:= M

where M was any Map, would always result in 'true'.

This commit fixes this issue by first comparing sizes for
both terms and then checking for size zero.
compiler: Fix error message printout on compile error

Use correct stack in printout.
Fix a qlc bug where filters were erroneously optimized away

Thanks to Sam Bobroff for reporting the bug.
Merge branch 'egil/fix-compiler-error-msg'

* egil/fix-compiler-error-msg:
  compiler: Fix error message printout on compile error
Merge branch 'egil/fix-maps-eq'

* egil/fix-maps-eq:
  erts: Fix Map cmp exact equal of an empty map
ssl: Improved documentation of the cacertfile option
Merge branch 'ia/ssl/doc-imp/OTP-11759'

* ia/ssl/doc-imp/OTP-11759:
  ssl: Improved documentation of the cacertfile option
ssl: Add input sanity check

Avoid puzzling behavior due to options being disregarded if they
are not key value tuples.
Merge branch 'ia/ssl/proplist-input-check/OTP-11760'

* ia/ssl/proplist-input-check/OTP-11760:
  ssl: Add input sanity check
Merge branch 'hb/stdlib/qlc_fix/OTP-11758'

* hb/stdlib/qlc_fix/OTP-11758:
  Fix a qlc bug where filters were erroneously optimized away
Return warnings for unknown types and functions in Erlang Mode

The warnings about unknown types and functions are now returned
when calling Dialyzer from Erlang, in particular from an escript.

When calling Dialyzer from the command line the warnings about unknown
types and functions are output last as before; and when using the GUI
the warnings are displayed in a pop-up window, as before.
Introduce a new warning option, 'no_unknown'

Not (yet) documented.