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/ex_docmd.c b/src/ex_docmd.c
index ea6dbb6..be95992 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -3082,6 +3082,7 @@
     return OK;
 }
 
+#if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * Return TRUE if "cmod" has anything set.
  */
@@ -3110,6 +3111,7 @@
     }
     return FALSE;
 }
+#endif
 
 /*
  * Apply the command modifiers.  Saves current state in "cmdmod", call
@@ -3393,6 +3395,7 @@
     *d = NUL;
 }
 
+#if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * If "start" points "&opt", "&l:opt", "&g:opt" or "$ENV" return a pointer to
  * the name.  Otherwise just return "start".
@@ -3413,6 +3416,7 @@
 	name += 1;
     return name;
 }
+#endif
 
 /*
  * Find an Ex command by its name, either built-in or user.