* lib/autoconf/c.m4 (AC_LANG(Objective C), AC_LANG_OBJC)

* lib/autoconf/c.m4 (AC_LANG(Objective C), AC_LANG_OBJC)
(_AC_LANG_ABBREV(Objective C), _AC_LANG_PREFIX(Objective C))
(AC_LANG_SOURCE(Objective C), AC_LANG_PROGRAM(Objective C))
(AC_LANG_CALL(Objective C), AC_LANG_FUNC_LINK_TRY(Objective C))
(AC_LANG_BOOL_COMPILE_TRY(Objective C))
(AC_LANG_INT_SAVE(Objective C), AC_LANG_PREPROC(Objective C))
(AC_PROG_OBJCPP, AC_LANG_COMPILER(Objective C), AC_PROG_OBJC)
(_AC_PROG_OBJC_G): New macros.
(_AC_ARG_VAR_CPPFLAGS): Adjusted.
* doc/autoconf.texi (Objective C Compiler): New node.
(Preset Output Variables): Document OBJCFLAGS.
(Language Choice): Document `Objective C' language.
(Fortran Compiler): Fix typo.
* NEWS: Updated.
Inspired by a patch from David M. Lloyd <dmlloyd@tds.net>.