Compile errors on 2013.57

[Hans Harder]

I get compile errors with the new version, because I compile this in a
uclib environment without zlib.
I use ./configure --disable-zlib

In common-kex.c I run into compile errors.

common-kex.o(.text+0x203): In function `switch_keys':
: undefined reference to `gen_new_zstream_recv'
common-kex.o(.text+0x257): In function `switch_keys':
: undefined reference to `gen_new_zstream_trans'
collect2: ld returned 1 exit status
make: *** [dropbear] Error 1

Probably this will solve it.

--- common-kex.c        2013-04-16 14:44:42.000000000 -0600
+++ common-kex.c    2013-04-16 15:08:54.000000000 -0600
@@ -171,14 +171,18 @@ static void switch_keys() {
        }
        if (ses.kexstate.recvnewkeys && ses.newkeys->recv.valid) {
                TRACE(("switch_keys recv"))
+#ifndef DISABLE_ZLIB
                gen_new_zstream_recv();
+#endif
                ses.keys->recv = ses.newkeys->recv;
                m_burn(&ses.newkeys->recv, sizeof(ses.newkeys->recv));
                ses.newkeys->recv.valid = 0;
        }
        if (ses.kexstate.sentnewkeys && ses.newkeys->trans.valid) {
                TRACE(("switch_keys trans"))
+#ifndef DISABLE_ZLIB
                gen_new_zstream_trans();
+#endif
                ses.keys->trans = ses.newkeys->trans;
                m_burn(&ses.newkeys->trans, sizeof(ses.newkeys->trans));
                ses.newkeys->trans.valid = 0;