Just rebuilding autoconf on an SL50 machine does indeed seem to fix it:

$ rpm -q autoconf
autoconf-2.59-12.JSPTEST.noarch
$ rpm -ql autoconf | egrep m4f | xargs egrep 'frozen state file gen'
/usr/share/autoconf/autoconf/autoconf.m4f:# This is a frozen state file generated by GNU M4 1.4.5
/usr/share/autoconf/autotest/autotest.m4f:# This is a frozen state file generated by GNU M4 1.4.5
/usr/share/autoconf/m4sugar/m4sh.m4f:# This is a frozen state file generated by GNU M4 1.4.5
/usr/share/autoconf/m4sugar/m4sugar.m4f:# This is a frozen state file generated by GNU M4 1.4.5

and now the cups package seems to build as expected...  Was the autoconf 
built this way to work round some other problem?  I'm rather puzzled that 
I'd not hit it before but maybe packages using autoconf just don't often 
check for mkstemp.

  -- Jon