devel/zthread won't build on 5.3-BETA5

[Guy Middleton]

On 5.3-BETA5 with the default compiler (G++ 3.4.2), zthread won't compile:

c++ -DHAVE_CONFIG_H -I. -I. -I. -I../include -O -pipe -Wall -DNDEBUG -O -pipe
-Wall -DNDEBUG -MT AtomicCount.lo -MD -MP -MF .deps/AtomicCount.Tpo -c
AtomicCount.cxx  -fPIC -DPIC
In file included from vanilla/SimpleAtomicCount.cxx:25,
                 from AtomicCount.cxx:50:
../include/zthread/Guard.h: In destructor `ZThread::Guard<LockType,
LockingPolicy>::~Guard()':
../include/zthread/Guard.h:493: error: there are no arguments to `isDisabled'
that depend on a template parameter, so a declaration of `isDisabled' must be
available
../include/zthread/Guard.h:493: error: (if you use `-fpermissive', G++ will
accept your code, but allowing the use of an undeclared name is deprecated)
gmake[3]: *** [AtomicCount.lo] Error 1
gmake[3]: Leaving directory `/usr/ports/devel/zthread/work/ZThread-2.3.1/src'
gmake[2]: *** [all-recursive] Error 1
gmake[2]: Leaving directory `/usr/ports/devel/zthread/work/ZThread-2.3.1/src'
gmake[1]: *** [all] Error 2
gmake[1]: Leaving directory `/usr/ports/devel/zthread/work/ZThread-2.3.1/src'
gmake: *** [all-recursive] Error 1
*** Error code 2


It works fine when compiled with G++ 3.2.3.