vchoi_fork

[svn-r17392] I added a detection for the correctness of converting from unsigned long to float in the 
configure.in.  The Pathscale compiler on Sandia's Linux machine misinterprets the values of 
unsigned long as negative during the conversion to float, when the first bit of unsigned long
is on.  

Tested on jam.  Need to test it on Sandia's machine.