IcyMetadataParser: implement charset conversion

test/meson.build

@@ -335,6 +335,7 @@ if curl_dep.found()
     '../src/LogBackend.cxx',
     include_directories: inc,
     dependencies: [
+      icu_dep,
       tag_dep,
       gtest_dep,
     ],

test/test_icy_parser.cxx

@@ -18,7 +18,11 @@ icy_parse_tag(const char *p)
 {
 	char *q = strdup(p);
 	AtScopeExit(q) { free(q); };
-	return icy_parse_tag(q, q + strlen(q));
+	return icy_parse_tag(
+#ifdef HAVE_ICU_CONVERTER
+			     nullptr,
+#endif
+			     q, q + strlen(q));
 }
 
 static void