[Exiv2] update to 0.27.1

[jasjuang]

Tested on windows and everything works like usual.

Note that there is a breaking change on cmake usage, instead of target_link_libraries(main PRIVATE xmp exiv2lib) now it becomes target_link_libraries(main PRIVATE exiv2-xmp exiv2lib)

[nartes]

@jasjuang, please test linux build. [1] it's not a complete package upgrade.

1. iconv.patch doesn't apply

The following packages will be built and installed:
    exiv2[core]:x64-linux
Starting package 1/1: exiv2:x64-linux
Building package exiv2[core]:x64-linux...
-- Using cached /home/nartes/Documents/current/clothes-search/deps/vcpkg/downloads/Exiv2-exiv2-0.27.1.tar.gz
-- Extracting source /home/nartes/Documents/current/clothes-search/deps/vcpkg/downloads/Exiv2-exiv2-0.27.1.tar.gz
-- Applying patch iconv.patch
-- Applying patch failed. This is expected if this patch was previously applied.
-- Using source at /home/nartes/Documents/current/clothes-search/deps/vcpkg/buildtrees/exiv2/src/0.27.1-0acca1f921
-- Configuring x64-linux-dbg
^CError: Building package exiv2:x64-linux failed with: BUILD_FAILED
Please ensure you're using the latest portfiles with `.\vcpkg update`, then
submit an issue at https://github.com/Microsoft/vcpkg/issues including:
  Package: exiv2:x64-linux
  Vcpkg version: 2019.06.21-unknownhash

Additionally, attach any relevant sections from the log files above.

2. as a result Iconv::Iconv dependency breaks build, since it should be replaced

[jasjuang]

@nartes Unfortunately I don't have a vcpkg linux setup to test. If there's an error on linux I think the CI should catch it. Do you have any idea why it didn't?