Fixed a typo in type_wrapper.h (#218)

_MSCV_LANG should read _MSVC_LANG.

Author: rturrado

hdr/sqlite_modern_cpp/type_wrapper.h

@@ -10,7 +10,7 @@
 #endif
 #endif
 #ifdef __has_include
-#if (__cplusplus > 201402 || _MSCV_LANG > 201402) && __has_include(<optional>)
+#if (__cplusplus > 201402 || _MSVC_LANG > 201402) && __has_include(<optional>)
 #define MODERN_SQLITE_STD_OPTIONAL_SUPPORT
 #elif __has_include(<experimental/optional>) && __apple_build_version__ < 11000000
 #define MODERN_SQLITE_EXPERIMENTAL_OPTIONAL_SUPPORT