Fix builds with system LZMA when using versions of CMake before 3.14

The "FindLibLZMA.cmake" module in CMake versions prior to 3.14 do not
set an alias like how Externals/liblzma/CMakeLists.txt does, so builds
performed using one of those older CMake versions will fail if the
system LZMA library is detected. To fix this, we need to link against
"lzma" instead of "LibLZMA::LibLZMA".

Fixes: b59ef81 ("WIA: Implement bzip2, LZMA, and LZMA2 decompression")

Source/Core/DiscIO/CMakeLists.txt

@@ -59,7 +59,7 @@ add_library(discio
 target_link_libraries(discio
 PUBLIC
   BZip2::BZip2
-  LibLZMA::LibLZMA
+  lzma
   zstd
 
 PRIVATE