Reflect change from CONFIGURATION to EMACS_CONFIGURATION.

Also set it to correct three-part value.

msdos/sed2.inp

@@ -24,6 +24,6 @@
 /^#undef HAVE_FTIME *$/s/undef/define/
 s/^#define USER_FULL_NAME .*$/#define USER_FULL_NAME (getenv ("NAME"))/
 s/^#undef STACK_DIRECTION *$/#define STACK_DIRECTION -1/
-s/^#undef CONFIGURATION *$/#define CONFIGURATION "msdos"/
+s/^#undef EMACS_CONFIGURATION *$/#define EMACS_CONFIGURATION "i386-unknown-msdos"/
 s!^#undef config_opsysfile *$!#define config_opsysfile "s/msdos.h"!
 s!^#undef config_machfile *$!#define config_machfile "m/dos386.h"!