[opam] fix dependencies

dune-project

@@ -34,7 +34,7 @@
   "camlp5"
   "camlp-streams"
   ("conf-llvm" (>= 11.0.0)) ; note: includes depexts
-  ("conf-libclang-cpp" (>= 11.0.0))
+  ("conf-libclang" (>= 11.0.0))
      ; conf-libclang-cpp:version should be equal to conf-llvm:version but
      ; this can't be enforced through opam dependencies yet
   "conf-cmake" ; note: includes depexts

frama-clang.opam

@@ -8,7 +8,7 @@ depends: [
   "camlp5"
   "camlp-streams"
   "conf-llvm" {>= "11.0.0"}
-  "conf-libclang-cpp" {>= "11.0.0"}
+  "conf-libclang" {>= "11.0.0"}
   "conf-cmake"
   "odoc" {with-doc}
 ]