patch 8.2.4038: various code not used when features are disabled

Problem:    Various code not used when features are disabled.
Solution:   Add #ifdefs. (Dominique Pellé, closes #9491)
diff --git a/src/option.c b/src/option.c
index dd51593..169f929 100644
--- a/src/option.c
+++ b/src/option.c
@@ -753,6 +753,7 @@
 	options[opt_idx].def_val[VI_DEFAULT] = (char_u *)(long_i)val;
 }
 
+#if defined(FEAT_PROP_POPUP) || defined(PROTO)
 /*
  * Set all window-local and buffer-local options to the Vim default.
  * local-global options will use the global value.
@@ -784,6 +785,7 @@
     curwin = save_curwin;
     curbuf = curwin->w_buffer;
 }
+#endif
 
 #if defined(EXITFREE) || defined(PROTO)
 /*
@@ -5535,6 +5537,7 @@
     return options[opt_idx].var;
 }
 
+#if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * Return the full name of the option at 'opt_idx'
  */
@@ -5543,6 +5546,7 @@
 {
     return (char_u *)options[opt_idx].fullname;
 }
+#endif
 
 /*
  * Get the value of 'equalprg', either the buffer-local one or the global one.