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_unix.h

@@ -303,6 +303,10 @@ typedef struct dsc$descriptor   DESC;
 # endif
 #endif
 
+#ifndef VIM_DEFAULTS_FILE
+# define VIM_DEFAULTS_FILE "$VIMRUNTIME/defaults.vim"
+#endif
+
 #ifndef EVIM_FILE
 # define EVIM_FILE	"$VIMRUNTIME/evim.vim"
 #endif