Update ImageMagick7 to 7.0.8.14 [1]

• Add option for ISO/IEC 23008-12:2017 HEIF suport [1]
• Add option for RAW support (from IM6).
• Convert a number of options to optionhelpers (sync from IM6).
• Add comment to the patch-config_policy.xml file why it still needed.

PR: 230788 (based on) [1]
Submitted by: Sebastian Steinmetz <freebsd-2018@sebastiansteinmetz.ch>