Avoid unnecessary redefinition of atoll() under MSVC 2013

atoll() was added to the MSVC standard library under MSVC 2013
so we don't need our own definition of it.

MD-20088
test: none: Build fix

src/UpdaterOptions.cpp

@@ -9,7 +9,8 @@
 #include <cstdlib>
 #include <iostream>
 
-#ifdef PLATFORM_WINDOWS
+#if defined(PLATFORM_WINDOWS) && (_MSC_VER < 1800)
+// atoll() was added in MSVC 2013
 long long atoll(const char* string)
 {
 	return _atoi64(string);