patch 8.1.0578: cannot disable arabic, rightleft and farsi in configure

Problem:    Cannot disable arabic, rightleft and farsi in configure.
Solution:   Add configur flags. (Diego Fernando Carrión, closes #1867)
diff --git a/src/feature.h b/src/feature.h
index 6ae3ac2..9e87345 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -263,7 +263,7 @@
  *
  * Disabled for EBCDIC as it requires multibyte.
  */
-#if defined(FEAT_BIG) && !defined(EBCDIC)
+#if defined(FEAT_BIG) && !defined(DISABLE_RIGHTLEFT) && !defined(EBCDIC)
 # define FEAT_RIGHTLEFT
 #endif
 
@@ -273,7 +273,7 @@
  *
  * Disabled for EBCDIC as it requires multibyte.
  */
-#if defined(FEAT_BIG) && !defined(EBCDIC)
+#if defined(FEAT_BIG) && !defined(DISABLE_FARSI) && !defined(EBCDIC)
 # define FEAT_FKMAP
 #endif
 #ifdef FEAT_FKMAP
@@ -288,7 +288,7 @@
  *
  * Disabled for EBCDIC as it requires multibyte.
  */
-#if defined(FEAT_BIG) && VIM_SIZEOF_INT >= 4 && !defined(EBCDIC)
+#if defined(FEAT_BIG) && !defined(DISABLE_ARABIC) && VIM_SIZEOF_INT >= 4 && !defined(EBCDIC)
 # define FEAT_ARABIC
 #endif
 #ifdef FEAT_ARABIC