win: enable anonymous structs for Visual Studio 2015  and later
/* We're compiling for C11 or this is the MSVC compiler. In either
* case, anonymous structs are available, so use them. */
# define CGLM_USE_ANONYMOUS_STRUCT 1
+# elif defined(_MSC_VER) && (_MSC_VER >= 1900) /* Visual Studio 2015 */
+ /* We can support anonymous structs
+ * since Visual Studio 2015 or 2017 (1910) maybe? */
+# define CGLM_USE_ANONYMOUS_STRUCT 1
# else
/* Otherwise, we're presumably building for C99 or C89 and can't rely
* on anonymous structs being available. Turn them off. */
