apache2: Upgrade 2.4.16 -> 2.4.18

1. Upgrade apache2 from 2.4.16 to 2.4.18

The changes in 2.4.18 is shown in following URL.
http://ftp.meisei-u.ac.jp/mirror/apache/dist//httpd/CHANGES_2.4.18

2. Delete patch file npn-patch-2.4.7.patch due to this patch file can not be applied to the apache2 2.4.18's source code.

The NPN support was removed with r1676004. NPN is now quite unlikely to find its way into a stable release.
https://bz.apache.org/bugzilla/show_bug.cgi?id=52210



Signed-off-by: Fan Xin <fan.xin@jp.fujitsu.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>