acinclude.m4 (GLIBCPP_CHECK_CTYPE_SUPPORT): check for DJGPP <ctype.h>

* acinclude.m4 (GLIBCPP_CHECK_CTYPE_SUPPORT): check for DJGPP <ctype.h>
(LIB_AC_PROG_CXX): replace [/\\] with [\\/] to work around older
bash bug.
* aclocal.m4: regenerated.
* configure.target: set os_include_dir to config/os/djgpp under DJGPP.
* configure: regenerated.
* config/os/djgpp, config/os/djgpp/bits: new directories.
* config/os/djgpp/bits/ctype_base.h,
config/os/djgpp/bits/ctype_inline.h,
config/os/djgpp/bits/ctype_noninline.h,
config/os/djgpp/bits/os_defines.h: new files.

From-SVN: r38958