locale_facets.tcc (num_get::_M_extract_float): Constify a couple of variables.

2003-10-04  Paolo Carlini  <pcarlini@unitus.it>

	* include/bits/locale_facets.tcc (num_get::_M_extract_float):
	Constify a couple of variables.
	(num_get::do_get(..., bool&)): Constify __c; prefer *__beg,
	++__beg to *__beg++.

From-SVN: r72093