Remove patch which has been rolled in from libxml2 upstream.

third_party/libxml/chromium/libxml2-2.9.4-security-CVE-2017-7375-xmlParsePEReference-xxe.patch

Index: third_party/libxml/chromium/libxml2-2.9.4-security-CVE-2017-7375-xmlParsePEReference-xxe.patch
diff --git a/third_party/libxml/chromium/libxml2-2.9.4-security-CVE-2017-7375-xmlParsePEReference-xxe.patch b/third_party/libxml/chromium/libxml2-2.9.4-security-CVE-2017-7375-xmlParsePEReference-xxe.patch
deleted file mode 100644
index 5548b880d1ba1121c5ccd1afc2f9729cbd7ad4b3..0000000000000000000000000000000000000000
--- a/third_party/libxml/chromium/libxml2-2.9.4-security-CVE-2017-7375-xmlParsePEReference-xxe.patch
+++ /dev/null
@@ -1,19 +0,0 @@
-https://bugzilla.gnome.org/show_bug.cgi?id=780691
-
---- src/parser.c
-+++ src/parser.c
-@@ -8130,6 +8130,14 @@ xmlParsePEReference(xmlParserCtxtPtr ctxt)
- 	    if (xmlPushInput(ctxt, input) < 0)
- 		return;
- 	} else {
-+	    if ((entity->etype == XML_EXTERNAL_PARAMETER_ENTITY) &&
-+	        ((ctxt->options & XML_PARSE_NOENT) == 0) &&
-+	        ((ctxt->options & XML_PARSE_DTDVALID) == 0) &&
-+	        ((ctxt->options & XML_PARSE_DTDLOAD) == 0) &&
-+	        ((ctxt->options & XML_PARSE_DTDATTR) == 0) &&
-+	        (ctxt->replaceEntities == 0) &&
-+	        (ctxt->validate == 0))
-+	        return;
- 	    /*
- 	     * TODO !!!
- 	     * handle the extra spaces added before and after