File mailsync-gcc9.diff of Package mailsync

diff --git a/acinclude/ac_with_md5.m4 b/acinclude/ac_with_md5.m4
index 78ed246..2e1da16 100644
--- a/acinclude/ac_with_md5.m4
+++ b/acinclude/ac_with_md5.m4
@@ -38,7 +38,7 @@ AC_DEFUN([AC_WITH_MD5],[
     void mm_nocritical(MAILSTREAM*a){}
     void mm_notify(MAILSTREAM*a,char*b,long c){}
     void mm_login(NETMBX*a,char*b,char*c,long d){}
-    long mm_diskerror(MAILSTREAM*a,long b,long c){}
+    long mm_diskerror(MAILSTREAM*a,long b,long c){ return 0; }
     void mm_status(MAILSTREAM*a,char*b,MAILSTATUS*c){}
     void mm_lsub(MAILSTREAM*a,int b,char*c,long d){}
     void mm_list(MAILSTREAM*a,int b,char*c,long d){}