More details about this patch are on http://bugs.debian.org/529838
The bug and the patch were forwarded to upstream, please see 
http://bugs.mutt.org/3239

--- a/configure.ac
+++ b/configure.ac
@@ -690,10 +690,10 @@
   then
     AC_MSG_WARN([SSL support is only useful with POP, IMAP or SMTP support])
   else
-    MUTT_AM_PATH_GNUTLS([$gnutls_prefix],
+    PKG_CHECK_MODULES(GNUTLS, gnutls,
       [dnl GNUTLS found
-      CPPFLAGS="$CPPFLAGS $LIBGNUTLS_CFLAGS"
-      MUTTLIBS="$MUTTLIBS $LIBGNUTLS_LIBS"
+      CPPFLAGS="$CPPFLAGS $GNUTLS_CFLAGS"
+      MUTTLIBS="$MUTTLIBS $GNUTLS_LIBS"
 
       AC_DEFINE(USE_SSL,1,[ Define if you want support for SSL. ])
       AC_DEFINE(USE_SSL_GNUTLS,1,[ Define if you want support for SSL via GNUTLS. ])