Minor, fix warnings on new stdlib API

In modules where allWarningsAsErrors is not yet enabled.

libraries/kotlinx-metadata/src/kotlinx/metadata/impl/readUtils.kt

@@ -37,7 +37,7 @@ fun ProtoBuf.Annotation.Argument.Value.readAnnotationArgument(strings: NameResol
 
     return when (type) {
         BYTE -> KmAnnotationArgument.ByteValue(intValue.toByte())
-        CHAR -> KmAnnotationArgument.CharValue(intValue.toChar())
+        CHAR -> KmAnnotationArgument.CharValue(intValue.toInt().toChar())
         SHORT -> KmAnnotationArgument.ShortValue(intValue.toShort())
         INT -> KmAnnotationArgument.IntValue(intValue.toInt())
         LONG -> KmAnnotationArgument.LongValue(intValue)

libraries/kotlinx-metadata/src/kotlinx/metadata/impl/writeUtils.kt

@@ -34,7 +34,7 @@ fun KmAnnotationArgument.writeAnnotationArgument(strings: StringTable): ProtoBuf
             }
             is KmAnnotationArgument.CharValue -> {
                 this.type = ProtoBuf.Annotation.Argument.Value.Type.CHAR
-                this.intValue = value.toLong()
+                this.intValue = value.code.toLong()
             }
             is KmAnnotationArgument.ShortValue -> {
                 this.type = ProtoBuf.Annotation.Argument.Value.Type.SHORT