patch 7.4.2111

Problem:    Defaults are very conservative.
Solution:   Move settings from vimrc_example.vim to defaults.vim.  Load
            defaults.vim if no .vimrc was found.

src/os_dos.h

@@ -25,6 +25,9 @@
 #ifndef USR_VIMRC_FILE3
 # define USR_VIMRC_FILE3	"$VIM\\_vimrc"
 #endif
+#ifndef VIM_DEFAULTS_FILE
+# define VIM_DEFAULTS_FILE	"$VIMRUNTIME\\defaults.vim"
+#endif
 #ifndef EVIM_FILE
 # define EVIM_FILE		"$VIMRUNTIME\\evim.vim"
 #endif