cmake: include GNUIncludeDirs for proper access to its variables

Author: Hugobros3

CMakeLists.txt

@@ -82,6 +82,8 @@ else()
     message("LLVM ${LLVM_VERSION} found")
 endif()
 
+include(GNUInstallDirs)
+
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)