COMMAND.COM as the shell.
# make extraclean
# Still more severe - delete backup and autosave files, too.
+# This gork is required for those who use a Unix-style shell, and
+# have SHELL in the environment pointing to it. Here we force
+# Make to use COMMAND.COM instead. This Makefile won't work otherwise.
+override SHELL=/dos/command
+override MAKESHELL=/dos/command
+
# Generate a full pathname of the top-level installation directory
top_srcdir := $(subst \,/,$(shell cd))