Use set for XRefTarget

Summary: Similar to D67763122. WIth both these changes we can make sure to test Hack DBs properly in https://www.internalfb.com/code/fbsource/[0158ba036922]/tools/skycastle/lib2/glean/dbs/www_hack_incr_diff_test.sky?lines=21%2C25

Reviewed By: simonmar

Differential Revision: D68210537

fbshipit-source-id: a10b853d03cd9212fb25e921ee3fe226d889b21d

glean/schema/cpp/schema.h

@@ -13906,7 +13906,7 @@ struct CallArgument {
   }
 }; // struct CallArgument
 
-struct FileCall : Predicate<std::tuple<Fact<facebook::glean::cpp::schema::Src::File>, facebook::glean::cpp::schema::Src::ByteSpan, std::vector<CallArgument>, boost::variant<Alt<0, std::tuple<>>, Alt<1, XRefTarget>>, boost::variant<Alt<0, std::tuple<>>, Alt<1, CallArgument>>, boost::variant<Alt<0, std::tuple<>>, Alt<1, Declaration>>, std::vector<XRefTarget>>> {
+struct FileCall : Predicate<std::tuple<Fact<facebook::glean::cpp::schema::Src::File>, facebook::glean::cpp::schema::Src::ByteSpan, std::vector<CallArgument>, boost::variant<Alt<0, std::tuple<>>, Alt<1, XRefTarget>>, boost::variant<Alt<0, std::tuple<>>, Alt<1, CallArgument>>, boost::variant<Alt<0, std::tuple<>>, Alt<1, Declaration>>, std::set<XRefTarget>>> {
   static const char* GLEAN_name() {
     return "hack.FileCall";
   }
@@ -29613,7 +29613,7 @@ struct ArgumentValue : Predicate<boost::variant<Alt<0, std::string>, Alt<1, std:
 struct SCHEMA {
   template<typename P> struct index;
   static constexpr size_t count = 1321;
-  static constexpr char schemaId[] = "6b1f4c87d9affa95bff4e43dc9e40170";
+  static std::string schemaId = "59d399727c5be908f526f7279d0e6ee1";
   template<size_t i> struct predicate;
 };
 

glean/schema/source/hack.angle

@@ -527,7 +527,7 @@ predicate FileCall :
     callee_xref: maybe XRefTarget,  # deprecated in favor of callee_xrefs
     dispatch_arg: maybe CallArgument,
     receiver_type: maybe Declaration,
-    callee_xrefs: [XRefTarget],
+    callee_xrefs: set XRefTarget,
   }
 
 # All uses of a declaration in a file. Note that the bytespan offsets are