Upgrade to libxml 2.9.2 and libxslt 1.1.28

third_party/libxml/patches/snprintf_win32config

Index: third_party/libxml/patches/snprintf_win32config
diff --git a/third_party/libxml/patches/snprintf_win32config b/third_party/libxml/patches/snprintf_win32config
deleted file mode 100644
index 3fec790de461a4d493671a80dc5fec278842db78..0000000000000000000000000000000000000000
--- a/third_party/libxml/patches/snprintf_win32config
+++ /dev/null
@@ -1,14 +0,0 @@
-diff --git a/third_party/libxml/src/include/win32config.h b/third_party/libxml/src/include/win32config.h
-index 3fc9be5..5112ce6 100644
---- a/third_party/libxml/src/include/win32config.h
-+++ b/third_party/libxml/src/include/win32config.h
-@@ -95,7 +95,9 @@ static int isnan (double d) {
- 
- #if defined(_MSC_VER)
- #define mkdir(p,m) _mkdir(p)
-+#if _MSC_VER < 1900
- #define snprintf _snprintf
-+#endif
- #if _MSC_VER < 1500
- #define vsnprintf(b,c,f,a) _vsnprintf(b,c,f,a)
- #endif