locale_facets.tcc (num_put<>::_M_insert_int): When ios_base::showpos and the type is signed and the value is zero, prepend +.

2007-11-26  Paolo Carlini  <pcarlini@suse.de>

	* include/bits/locale_facets.tcc (num_put<>::_M_insert_int): When
	ios_base::showpos and the type is signed and the value is zero,
	prepend +.
	* testsuite/22_locale/num_put/put/char/12.cc: New.
	* testsuite/22_locale/num_put/put/wchar_t/12.cc: Likewise.

From-SVN: r130460