Update libxml to 2.7.7.

third_party/libxml/config.h.in

Index: third_party/libxml/config.h.in
diff --git a/third_party/libxml/config.h.in b/third_party/libxml/config.h.in
index f8435d4faebfbae182840e436156a73acee39d1c..d60f3627cd7d07d816620a18c3408a2a925fb2ef 100644
--- a/third_party/libxml/config.h.in
+++ b/third_party/libxml/config.h.in
@@ -85,6 +85,9 @@
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
+/* Define to 1 if you have the <inttypes.h.h> header file. */
+#undef HAVE_INTTYPES_H_H
+
 /* Define if isinf is there */
 #undef HAVE_ISINF
 
@@ -133,6 +136,9 @@
 /* Define to 1 if you have the <netinet/in.h> header file. */
 #undef HAVE_NETINET_IN_H
 
+/* Define to 1 if you have the <poll.h> header file. */
+#undef HAVE_POLL_H
+
 /* Define to 1 if you have the `printf' function. */
 #undef HAVE_PRINTF
 
@@ -249,6 +255,10 @@
 /* Define as const if the declaration of iconv() needs const. */
 #undef ICONV_CONST
 
+/* Define to the sub-directory in which libtool stores uninstalled libraries.
+   */
+#undef LT_OBJDIR
+
 /* Name of package */
 #undef PACKAGE
 
@@ -264,6 +274,9 @@
 /* Define to the one symbol short name of this package. */
 #undef PACKAGE_TARNAME
 
+/* Define to the home page for this package. */
+#undef PACKAGE_URL
+
 /* Define to the version of this package. */
 #undef PACKAGE_VERSION