message: Mono: Don't kill compilation if PkgConfig isn't installed.
diff: -find_package(PkgConfig REQUIRED)
  +find_package(PkgConfig)
  +
  +if (PKGCONFIG_FOUND)
  pkg_check_modules(MONO mono-2)
  if (${MONO_FOUND})
  @@ -8,3 +10,4 @@ if (${MONO_FOUND})
  target_include_directories(Mono PUBLIC ${MONO_INCLUDE_DIRS})
  target_compile_options(Mono PUBLIC ${MONO_CFLAGS_OTHER})
  endif()
  +endif()
  \ No newline at end of file
  