wm: fix WHEEL event translation

Fixes #1242.
vfs: add vfs handle header to single_file header

Fixes #1238.
vfs: add Rtc_file_system

The Rtc_file_system reads the current time from a Rtc_session and
provides the time as '%Y-%m-%d %H:%M\n' to all users of the vfs
node.

Fixes #1238.
openssl: use Genode specific RAND backend

The backend merely provides simpler access to '/dev/random' because
on Genode the common random device checks are unnecessary.

Fixes #1236.
openssl: update to version 1.0.1i

Just a normal version bump, though we should revise the openssl port
regarding explicit memset() etc. issues.

Fixes #1236.
libssl: use platform specific mk files

Instead of checking the target platform in the mk file use the common
pattern of providing a mk file for each platform.

Fixes #1236.
libcrypto: use platform specific mk files

Instead of checking the target platform in the mk file use the common
pattern of providing a mk file for each platform.

Fixes #1236.
libcrypto: remove MD2, RC5 and store

Remove components that are disabled upstream.

Fixes #1236.
libc: add support for Rtc_file_system

Fixes #1241.
libc: utilize Rtc_file_system in time functions

Fixes #1241.
libc: add support for external vfs file systems

These file systems are provided on-demand by loading a shared library
when the fstab node is traversed. By convention this library is named
after the file system it provides. For example a file system that
provides a 'random' file system node is called 'vfs_random.lib.so'. It
is still possible to give the the node another name in the vfs. The
following code snippts illustrates this matter:

! [...]
! <config>
!   <libc>
!     <vfs>
!       <dir name="dev"> <jitterentropy name="random"/> </dir>
!     </vfs>
!   </libc>
! </config>
! [...]

Here the jitterentropy file system, implemented in
'vfs_jitterentropy.lib.so' provides a file system node named 'random'
in the 'dev' directory. When traversing the vfs section the libc will
try to load 'vfs_jitterentropy.lib.so' but programs may access the
file system only via '/dev/random'.

Fixes #1240.