PR binutils/2876

PR binutils/2876
* configure.in: Check for the mkstemp and mkdtemp functions.
* configure: Regenerate.
* config.in (HAVE_MKDTEMP): New potential define.
(MAKE_MKSTEMP): Likewise.
* bucomm.c (make_tempname): Use mkstemp if it is available.
* make_tempdir): New function: Create a temporary directory using mkdtemp, if
it is available.
* bucomm.h (make_tempdir): New prototype.
* objcopy.c (copy_archive): Use make_tempdir if it is available.
  (strip_main): Produce an warning message if a temporary file could not be
  (copy_main): Likewise.
* ar.c (write_archive): Likewise.