[WASM] Define and declare swift_isClassType as swiftcc because it got to be called from swift

Author: kateinoigakukun

include/swift/Runtime/RuntimeFunctions.def

@@ -1172,7 +1172,7 @@ FUNCTION(ConformsToProtocol,
 
 // bool swift_isClassType(type*);
 FUNCTION(IsClassType,
-         swift_isClassType, C_CC, AlwaysAvailable,
+         swift_isClassType, SwiftCC, AlwaysAvailable,
          RETURNS(Int1Ty),
          ARGS(TypeMetadataPtrTy),
          ATTRS(ZExt, NoUnwind, ReadNone))

stdlib/public/runtime/Casting.cpp

@@ -3205,7 +3205,7 @@ const Metadata *swift::_swift_class_getSuperclass(const Metadata *theClass) {
 }
 
 // Called by compiler-generated cast code.
-SWIFT_RUNTIME_STDLIB_API
+SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
 bool swift_isClassType(const Metadata *type) {
   return Metadata::isAnyKindOfClass(type->getKind());
 }