Is your feature request related to a problem? Please describe.
Currently portmidi can't be build on linux using vcpkg

Proposed solution
Make vcpkg be able to build portmidi for linux.

Describe alternatives you've considered
None

Additional context
Information for installing portmidi: https://sourceforge.net/p/portmedia/wiki/Installing_portmidi_on_Linux/

current log from vcpkg:

-- Installing port from location: /home/baklap4/repos/performous/vcpkg/buildtrees/versioning/versions/portmidi/16f079de23d02226d49bd22659392d85e568528e
CMake Error at scripts/cmake/vcpkg_fail_port_install.cmake:96 (message):
  Target 'linux' not supported by portmidi!