* configure.in (LIBX11_MACHINE, HAVE_XFREE386): Remove code

* configure.in (LIBX11_MACHINE, HAVE_XFREE386): Remove code
dealing with obsolete variables.

* fakemail.c (MAIL_PROGRAM_NAME): Remove unused conditional.
(main): Replace MAIL_PROGRAM_NAME with its value.

* src/Makefile.in:
* src/emacs.c:
* src/gmalloc.c:
* src/keyboard.c:
* src/lisp.h:
* src/m/ibm370aix.h:
* src/process.c:
* src/regex.c:
* src/s/hpux.h:
* src/sysdep.c:
* src/sysselect.h:
* src/systty.h:
* src/unexec.c:
* src/w32term.c:
* src/xsmfns.c:
* src/xterm.c: Remove code that deals with obsolete variables.

* s/msdos.h (DONT_NEED_ENVIRON): Don't define.

* ecrt0.c: Replace the DONT_NEED_ENVIRON test with MSDOS test,
nothing else needs it anymore.