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

third_party/libxml/src/runtest.c

 /*
  * runtest.c: C program to run libxml2 regression tests without
  *            requiring make or Python, and reducing platform dependancies
  *            to a strict minimum.
  *
  * To compile on Unixes:
  * cc -o runtest `xml2-config --cflags` runtest.c `xml2-config --libs` -lpthread
  *
  * See Copyright for the status of this software.
  *
@@ skipping 2710 matching lines @@
 
 static int urip_success = 1;
 static int urip_current = 0;
 static const char *urip_testURLs[] = {
     "urip://example.com/a b.html",
     "urip://example.com/a%20b.html",
     "file:///path/to/a b.html",
     "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
 };
 static const char *urip_rcvsURLs[] = {
     /* it is an URI the strings must be escaped */
     "urip://example.com/a%20b.html",
     /* check that % escaping is not broken */
     "urip://example.com/a%20b.html",
     /* it's an URI path the strings must be escaped */
     "file:///path/to/a%20b.html",
@@ skipping 1720 matching lines @@
     return(ret);
 }
 
 #else /* ! LIBXML_OUTPUT_ENABLED */
 int
 main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED) {
     fprintf(stderr, "runtest requires output to be enabled in libxml2\n");
     return(1);
 }
 #endif