[Bug #6] sprintf() of %f on Windows(MSVCRT)

e$B%A%1%C%He(B #6 e$B$,99?7$5$l$^$7$?!#e(B (by Yuki S.)

e$BC4Ev<Te(B Usaku NAKAMURAe$B$+$ie(BNobuyoshi N.e$B$KJQ99e(B
e$BM%@hEYe(B Lowe$B$+$ie(BHighe$B$KJQ99e(B

e$B!VJ,$+$C$F$k$J$i%3%_%C%H$7$F!We(B(e$B$&$5$5$se(B)e$B$H$N$3$H$J$N$G$J$+$@$5$s$KG$$;$^$9!#e(B

http://redmine.ruby-lang.org/issues/show/6