[math] svn rev 48294 (2008-08-22) breaks gcc 3.2 builds

Hi,

This svn revision...

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r48294 | johnmaddock | 2008-08-22 05:51:40 -0700 (Fri, 22 Aug 2008) | 1 line

Merged changes from sandbox, and regenerated the docs.
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broke our gcc 3.2 builds. (Sorry I couldn't report this earlier; I was out of town.)

The minimal reproducer is simply:

#include <boost/math/special_functions/atanh.hpp>

% g++ -c -Iboost atanh.cpp
In file included from boost/boost/math/special_functions/atanh.hpp:24,
                 from atanh.cpp:1:
boost/boost/math/special_functions/log1p.hpp:456: new declaration `
   template<class T> T boost::math::log1pmx(T)'
boost/boost/math/special_functions/math_fwd.hpp:491: ambiguates old declaration 
   `template<class T> boost::math::tools::promote_args<RT, float, float, float, 
   float, float>::type boost::math::log1pmx(T)'

% g++ --version
g++ (GCC) 3.2.3 20030502 (Red Hat Linux 3.2.3-20)

I can make the error go away with the simple-minded patch below, just to prove that the ifdefed-out
code is the only problem for us.