Fix compilation error for egs_configure on Windows
Fix compilation error for egs_configure on Windows

Fix a type mismatch of a variable that resulted in compilation errors.
Newer compilers are strict about the type matching correctly, though
only the windows compiler mingw seemed to throw an error.

mchamberland/EGSnrc,mchamberland/EGSnrc,crcrewso/EGSnrc,crcrewso/EGSnrc,crcrewso/EGSnrc,mchamberland/EGSnrc,mchamberland/EGSnrc,nrc-cnrc/EGSnrc,crcrewso/EGSnrc,MartinMartinov/EGSnrc,MartinMartinov/EGSnrc,nrc-cnrc/EGSnrc,MartinMartinov/EGSnrc,MartinMartinov/EGSnrc,mchamberland/EGSnrc,mchamberland/EGSnrc,nrc-cnrc/EGSnrc,nrc-cnrc/EGSnrc,nrc-cnrc/EGSnrc,MartinMartinov/EGSnrc,crcrewso/EGSnrc