Update ImageMagick to 6.9.10.14 [1]

• Add PKGNAMESUFFIX and rename the directory. This was done to show that IM6 is not the "main" version. But still fully supported by upstream.
• Convert a number of options to optionhelpers.
• Add option for ISO/IEC 23008-12:2017 HEIF suport
• Add comment to pkg-descr explaining IM6's "legacy" tag.
• Add comment to the patch-config_policy.xml file why it still needed.

Please note that IM7 is not a drop in replacement due to library API and
command arguments changes. And as a result ports need to decide for themself
which version to use.

Chase these changes in all the ports that using IM6.

PR: 225102 (based on, only the version update) [1]
Submitted by: Pascal Christen <pascal.christen@hostpoint.ch>