patch 9.1.0312: heredocs are not supported for :commands

Problem:  heredocs are not supported for :commands
          (@balki)
Solution: Add heredoc support
          (Yegappan Lakshmanan)

fixes: #14491
closes: #14528

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/charset.c

@@ -2088,6 +2088,17 @@ skiptowhite(char_u *p)
     return p;
 }
 
+/*
+ * skiptowhite: skip over text until ' ' or '\t' or newline or NUL.
+ */
+    char_u *
+skiptowhite_or_nl(char_u *p)
+{
+    while (*p != ' ' && *p != '\t' && *p != NL && *p != NUL)
+	++p;
+    return p;
+}
+
 /*
  * skiptowhite_esc: Like skiptowhite(), but also skip escaped chars
  */