patch 8.1.1901: the +insert_expand feature is not always available

Problem:    The +insert_expand feature is not always available.
Solution:   Graduate the +insert_expand feature.
diff --git a/src/getchar.c b/src/getchar.c
index 2fb8438..eeb3342 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1481,7 +1481,6 @@
 }
 #endif
 
-#if defined(FEAT_INS_EXPAND) || defined(PROTO)
 /*
  * Return TRUE when reading keys from a script file.
  */
@@ -1490,7 +1489,6 @@
 {
     return scriptin[curscript] != NULL;
 }
-#endif
 
 /*
  * This function is called just before doing a blocking wait.  Thus after
@@ -1866,7 +1864,6 @@
 }
 #endif
 
-#if defined(FEAT_INS_EXPAND) || defined(FEAT_EVAL) || defined(PROTO)
 /*
  * Check if any character is available, also half an escape sequence.
  * Trick: when no typeahead found, but there is something in the typeahead
@@ -1882,7 +1879,6 @@
 	c = ESC;
     return c;
 }
-#endif
 
 /*
  * Call vpeekc() without causing anything to be mapped.
@@ -1963,12 +1959,9 @@
 	    && !(State == HITRETURN && (tb_c1 == CAR || tb_c1 == ' '))
 	    && State != ASKMORE
 	    && State != CONFIRM
-#ifdef FEAT_INS_EXPAND
 	    && !((ctrl_x_mode_not_default() && vim_is_ctrl_x_key(tb_c1))
 		    || ((compl_cont_status & CONT_LOCAL)
-			&& (tb_c1 == Ctrl_N || tb_c1 == Ctrl_P)))
-#endif
-	    )
+			&& (tb_c1 == Ctrl_N || tb_c1 == Ctrl_P))))
     {
 #ifdef FEAT_LANGMAP
 	if (tb_c1 == K_SPECIAL)