Remove TODO in Crystal::Loader on Windows (crystal-lang#14988)

This has been addressed by crystal-lang#14146 from outside the loader, and there is essentially only one TODO left for crystal-lang#11575.

src/compiler/crystal/loader/msvc.cr

@@ -185,7 +185,6 @@ class Crystal::Loader
   end
 
   private def open_library(path : String)
-    # TODO: respect `@[Link(dll:)]`'s search order
     LibC.LoadLibraryExW(System.to_wstr(path), nil, 0)
   end