patch 8.1.0805: too many #ifdefs

Problem:    Too many #ifdefs.
Solution:   Graduate FEAT_MBYTE, part 1.
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index 9fe22a3..60af27c 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -1957,7 +1957,7 @@
 		    if (IObuff[IOSIZE - 2] != NUL && IObuff[IOSIZE - 2] != NL)
 		    {
 			int n = IOSIZE - 2;
-# ifdef FEAT_MBYTE
+
 			if (enc_utf8)
 			{
 			    /* Move to the first byte of this char.
@@ -1968,7 +1968,6 @@
 			}
 			else if (has_mbyte)
 			    n -= mb_head_off(IObuff, IObuff + n);
-# endif
 			IObuff[n] = NL;
 			IObuff[n + 1] = NUL;
 		    }
@@ -4254,9 +4253,7 @@
     int		dbg_tick;	/* debug_tick when breakpoint was set */
     int		level;		/* top nesting level of sourced file */
 #endif
-#ifdef FEAT_MBYTE
     vimconv_T	conv;		/* type of conversion */
-#endif
 };
 
 #ifdef FEAT_EVAL
@@ -4593,7 +4590,6 @@
 # endif
 #endif
 
-#ifdef FEAT_MBYTE
     cookie.conv.vc_type = CONV_NONE;		/* no conversion */
 
     /* Read the first line so we can check for a UTF-8 BOM. */
@@ -4612,7 +4608,6 @@
 	    firstline = p;
 	}
     }
-#endif
 
     /*
      * Call do_cmdline, which will call getsourceline() to get the lines.
@@ -4683,9 +4678,7 @@
     fclose(cookie.fp);
     vim_free(cookie.nextline);
     vim_free(firstline);
-#ifdef FEAT_MBYTE
     convert_setup(&cookie.conv, NULL, NULL);
-#endif
 
     if (trigger_source_post)
 	apply_autocmds(EVENT_SOURCEPOST, fname_exp, fname_exp, FALSE, curbuf);
@@ -4924,7 +4917,6 @@
 	}
     }
 
-#ifdef FEAT_MBYTE
     if (line != NULL && sp->conv.vc_type != CONV_NONE)
     {
 	char_u	*s;
@@ -4937,7 +4929,6 @@
 	    line = s;
 	}
     }
-#endif
 
 #ifdef FEAT_EVAL
     /* Did we encounter a breakpoint? */
@@ -5194,7 +5185,6 @@
     void
 ex_scriptencoding(exarg_T *eap UNUSED)
 {
-#ifdef FEAT_MBYTE
     struct source_cookie	*sp;
     char_u			*name;
 
@@ -5219,7 +5209,6 @@
 
     if (name != eap->arg)
 	vim_free(name);
-#endif
 }
 
 #if defined(FEAT_EVAL) || defined(PROTO)