patch 8.1.0783: compiler warning for signed/unsigned

Problem:    Compiler warning for signed/unsigned.
Solution:   Add type cast.  Change type of buffer. (Ozaki Kiichi, closes #3827)

Author: brammool

src/main.c

@@ -1288,7 +1288,7 @@ main_loop(
 		 * string here. Don't reset keep_msg, msg_attr_keep() uses it
 		 * to check for duplicates. */
 		p = keep_msg;
-		msg_attr(p, keep_msg_attr);
+		msg_attr((char *)p, keep_msg_attr);
 		vim_free(p);
 	    }
 	    if (need_fileinfo)		/* show file info after redraw */

src/message.c

@@ -1389,9 +1389,9 @@ msg_putchar(int c)
 msg_putchar_attr(int c, int attr)
 {
 #ifdef FEAT_MBYTE
-    char	buf[MB_MAXBYTES + 1];
+    char_u	buf[MB_MAXBYTES + 1];
 #else
-    char	buf[4];
+    char_u	buf[4];
 #endif
 
     if (IS_SPECIAL(c))
@@ -1404,13 +1404,13 @@ msg_putchar_attr(int c, int attr)
     else
     {
 #ifdef FEAT_MBYTE
-	buf[(*mb_char2bytes)(c, (char_u *)buf)] = NUL;
+	buf[(*mb_char2bytes)(c, buf)] = NUL;
 #else
 	buf[0] = c;
 	buf[1] = NUL;
 #endif
     }
-    msg_puts_attr(buf, attr);
+    msg_puts_attr((char *)buf, attr);
 }
 
     void

src/version.c

@@ -791,6 +791,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    783,
 /**/
     782,
 /**/