MFH: r526071

graphics/libexif: Fix security vulnerabilities

• Fix CVE-2019-9278
  
  In libexif, there is a possible out of bounds write due to an integer overflow. This could lead to remote escalation of privilege in the media content provider with no additional execution privileges needed. User interaction is needed for exploitation.
• Fix a buffer read overflow in exif_entry_get_value
• Fix a buffer overread in exif_mnote_data_olympus_load

PR: 244060
Reported by: tj@mrsk.me (email)
Approved by: former maintainer
Security: 00f30cba-4d23-11ea-86ba-641c67a117d8

Approved by: ports-secteam (blanket, backport of security fixes)