imagemagick: Update to 6.8.8

Add ImageMagick to known licenses
The license checksum is changed due to year change in license text
-Copyright 1999-2013 ImageMagick Studio LLC, a non-profit organization dedicated to making software imaging solutions freely available.
+Copyright 1999-2014 ImageMagick Studio LLC, a non-profit organization dedicated to making software imaging solutions freely available.

Add suffix .im6 to binaries, this avoids conflicts with other packages
e.g. lmbench provides stream utility and imagemagick does too so when
both packages are being part of image we have conflicts. This resolves
it by renaming stream to stream.im6 to make it distinct

Signed-off-by: Khem Raj <raj.khem@gmail.com>