Use vfork(2) where exec(2) is immediately done
Rebuild configure to fix C++11 detection.

Missed in the clang-c++11-bdlib merge.
Merge branch 'maint'

* maint:
  Handle failure to find packdata rather than crashing.
Merge branch 'maint'

* maint:
  Update copyrights
Handle failure to find packdata rather than crashing.
Update copyrights
Merge branch 'maint'

* maint:
  Allow root in debug
Merge branch 'maint'

* maint:
  Add vim modeline everywhere
Allow root in debug
Add vim modeline everywhere
Use libelf to find the location of the settings struct
Give better hints to the compiler on this logic
Reading should use MAP_PRIVATE
Reduce duplicated logic
Give a hint that we are sequentially reading memory

At least on FreeBSD this lowered page faults from 92 to 84
Don't remove the main binary when making a copy
Update bdlib for AtomicFile
Don't try munmap(NULL)
Use bd::AtomicFile to avoid cross-device renaming from Tempfile

This also removes the need for making a copy of the file. The copy was
never setup be restored anyhow.
Write userfile with AtomicFile