Re-instate improved Mac OS X single-precision math function check that was erroneously removed by handegar in revision 1.181.
Re-instate improved Mac OS X single-precision math function check that
was erroneously removed by handegar in revision 1.181.

Alexpux/Coin3D,Alexpux/Coin3D,Alexpux/Coin3D,Alexpux/Coin3D