Optimize hasAttribute to avoid unnecessary list allocation (#222)

* Initial plan

* Optimize hasAttribute to use List.exists instead of filterAttributes

Co-authored-by: michael-schwarz <13812333+michael-schwarz@users.noreply.github.com>

* Remove obsolete sm comment before hasAttribute

Co-authored-by: michael-schwarz <13812333+michael-schwarz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: michael-schwarz <13812333+michael-schwarz@users.noreply.github.com>

Author: Copilot

src/cil.ml

@@ -1425,9 +1425,8 @@ and dropAttributes (anl: string list) (al: attributes) =
 and filterAttributes (s: string) (al: attribute list) : attribute list =
   List.filter (fun (Attr(an, _)) -> an = s) al
 
-(* sm: *)
 let hasAttribute s al =
-  (filterAttributes s al <> [])
+  List.exists (fun (Attr(an, _)) -> an = s) al
 
 
 type attributeClass =