Attempt to finish off araq cpp exceptions (#13695)

* config update
* disable a questionable test
* remove c++ exception handling IDs, new impl doesn't require it anymore
* C++ based exceptions finally work
* fixes bootstrapping problem in C++ mode
* teach GCC it's 2020 now
* more bugfixes for C++ based exception handling
* apply cooldome's patch
* another attempt to enable C++11
* bug fix

Co-authored-by: Araq <rumpf_a@web.de>
Co-authored-by: cooldome <ariabushenko@bk.ru>

lib/system/exceptions.nim

@@ -33,12 +33,6 @@ type
       trace: string
     else:
       trace: seq[StackTraceEntry]
-    when defined(nimBoostrapCsources0_19_0):
-      # see #10315, bootstrap with `nim cpp` from csources gave error:
-      # error: no member named 'raise_id' in 'Exception'
-      raise_id: uint # set when exception is raised
-    else:
-      raiseId: uint # set when exception is raised
     up: ref Exception # used for stacking exceptions. Not exported!
 
   Defect* = object of Exception ## \