Enforce all the source files to be encoded in UTF-8.

third_party/libxml/src/runtest.c

Index: third_party/libxml/src/runtest.c
diff --git a/third_party/libxml/src/runtest.c b/third_party/libxml/src/runtest.c
index fa925c10534ae76e539783d04b062a4a03d902f9..bc28795f6411445bfd8dc2045dc6b1cbe47b11e8 100644
--- a/third_party/libxml/src/runtest.c
+++ b/third_party/libxml/src/runtest.c
@@ -2728,7 +2728,7 @@ static const char *urip_testURLs[] = {
     "file:///path/to/a%20b.html",
     "/path/to/a b.html",
     "/path/to/a%20b.html",
-    "urip://example.com/résumé.html",
+    "urip://example.com/résumé.html",
     "urip://example.com/test?a=1&b=2%263&c=4#foo",
     NULL
 };