When a header search path contained a symlink, the suggested include
spelling could be wrong, as the files to insert provided by clangd are
always canonical (i.e. with the symlinks removed), but the search paths
(which come from flags), might not be. As files from Sema also come from
the VFS, they are also canonical, I think.
When trying to suggest the spelling of the include to insert, we should
always compare canonical paths. This corrects the include suggestion in