Consider "" a normal section, and fix calculation for zero
length section name string and key name string.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=8036
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=18099Signed-off-by: Claudio Fontana <claudio.fontana@gmail.com>
Signed-off-by: Vijay Kiran Kamuju <infyquest@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>