* minibuf.c: conform to C89 pointer rules

src/ChangeLog

@@ -18,6 +18,7 @@
 	* keyboard.c (echo_char, MULTI_LETTER_MOD, tty_read_avail_input):
 	Likewise.
 	* keymap.c (Ftext_char_description): Likewise.
+	* minibuf.c (Fread_buffer): Likewise.
 	* insdel.c (insert, insert_and_inherit, insert_before_markers):
 	(insert_before_markers_and_inherit, insert_1, insert_1_both):
 	Likewise.  This changes these functions' signatures, which is

src/minibuf.c

@@ -1091,7 +1091,7 @@ function, instead of the usual behavior.  */)
   (Lisp_Object prompt, Lisp_Object def, Lisp_Object require_match)
 {
   Lisp_Object args[4], result;
-  unsigned char *s;
+  char *s;
   int len;
   int count = SPECPDL_INDEX ();
 
@@ -1113,7 +1113,7 @@ function, instead of the usual behavior.  */)
 
 	  if (STRINGP (prompt))
 	    {
-	      s = SDATA (prompt);
+	      s = SSDATA (prompt);
 	      len = strlen (s);
 	      if (len >= 2 && s[len - 2] == ':' && s[len - 1] == ' ')
 		len = len - 2;