Some fixes to get LLDB compiling with MSVC 2015.

llvm-svn: 243174
diff --git a/lldb/source/Host/windows/Windows.cpp b/lldb/source/Host/windows/Windows.cpp
index f5d3143..cd2cfc9 100644
--- a/lldb/source/Host/windows/Windows.cpp
+++ b/lldb/source/Host/windows/Windows.cpp
@@ -202,6 +202,7 @@
     return 0;
 }
 
+#if _MSC_VER < 1900
 int snprintf(char *buffer, size_t count, const char *format, ...)
 {
     int old_errno = errno;
@@ -226,5 +227,6 @@
     va_end(argptr);
     return r;
 }
+#endif
 
 #endif // _MSC_VER