CMake: Add fallback for older unarr versions without FindPackage module

Author: selmf

CMakeLists.txt

@@ -79,11 +79,15 @@ set_property(CACHE OPENGL PROPERTY STRINGS "desktop" "angle" "force-angle"
 
 # Handle dependencies for backends
 if(DECOMPRESSION_BACKEND STREQUAL "unarr")
-  find_package("unarr" REQUIRED)
+  find_package("unarr")
+  # old unarr only ships PKGCONFIG
+  if(NOT unarr_FOUND)
+    pkg_check_modules(unarr IMPORTED_TARGET "libunarr" REQUIRED)
+  endif()
 elseif(DECOMPRESSION_BACKEND STREQUAL "7zip")
   find_package("7zip" REQUIRED)
 elseif(DECOMPRESSION_BACKEND STREQUAL "libarchive")
-  find_package("LibArchive::LibArchive" REQUIRED)
+  find_package("LibArchive" REQUIRED)
 else()
   message(FATAL_ERROR "No valid decompression backend specified.")
 endif()

compressed_archive/CMakeLists.txt

@@ -7,7 +7,11 @@ if(DECOMPRESSION_BACKEND STREQUAL "unarr")
                         unarr/extract_delegate.h)
   target_include_directories(cbx_backend PUBLIC unarr)
   target_compile_definitions(cbx_backend PUBLIC use_unarr)
-  target_link_libraries(cbx_backend unarr::unarr Qt::Core)
+  if(TARGET unarr:unarr)
+    target_link_libraries(cbx_backend unarr::unarr Qt::Core)
+  else()
+    target_link_libraries(cbx_backend PkgConfig::unarr Qt::Core)
+  endif()
 
 elseif(DECOMPRESSION_BACKEND STREQUAL "libarchive")