Merge branch 'rs/dup-array'

Code cleaning.

* rs/dup-array:
  use DUP_ARRAY
  add DUP_ARRAY
  do full type check in BARF_UNLESS_COPYABLE
  factor out BARF_UNLESS_COPYABLE
  mingw: make argv2 in try_shell_exec() non-const

diff --cc attr.c
Simple merge

diff --cc builtin/am.c
Simple merge

diff --cc compat/mingw.c
Simple merge

diff --cc git-compat-util.h
Simple merge