Avoid mail/mlmmj segfaults

[Frank Denis]

 Hello,
 
 Here's a trivial patch you may consider to add to mail/mlmmj.
 
 chomp() causes a segmentation fault on empty lines. I triggered it by
using an empty delimiter, but there are maybe other ways of triggering it.
 Submitted to the author.
 
$OpenBSD$
--- src/chomp.c.orig    Thu Aug 12 00:29:38 2004
+++ src/chomp.c Sun Feb 19 19:32:42 2006
@@ -30,7 +30,10 @@ char *chomp(char *str)
 
        if(str == NULL)
                return NULL;
-
+       if(*str == '\0' || *str == '\n') {
+               *str = '\0';
+               return str;
+       }
        i = strlen(str) - 1;
 
        while(str[i] == '\n') {