vim-patch:8.1.1632: build with EXITFREE but without +arabic fails

Problem:    Build with EXITFREE but without +arabic fails.
Solution:   Rename the function and adjust #ifdefs. (closes vim/vim#4613)
48ac671fe5

src/nvim/ex_getln.c

@@ -2495,7 +2495,7 @@ static void realloc_cmdbuff(int len)
 static char_u   *arshape_buf = NULL;
 
 # if defined(EXITFREE)
-void free_cmdline_buf(void)
+void free_arshape_buf(void)
 {
   xfree(arshape_buf);
 }

src/nvim/memory.c

@@ -648,7 +648,7 @@ void free_all_mem(void)
   // Free all option values.  Must come after closing windows.
   free_all_options();
 
-  free_cmdline_buf();
+  free_arshape_buf();
 
   /* Clear registers. */
   clear_registers();