Merge pull request #18 from kamrann/minor-fixes

Minor changes to preprocessor directives

include/uuid.h

@@ -18,10 +18,13 @@
 #include <gsl/span>
 
 #ifdef _WIN32
-#include <objbase.h>
-
-#define WIN32_LEAN_AND_MEAN        
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
+#include <objbase.h>
 #include <windows.h>
 #include <intrin.h>       
 #include <iphlpapi.h> 
@@ -697,7 +700,7 @@ namespace uuids
                bytes.byte15
             } };
          return uuid{ std::begin(arrbytes), std::end(arrbytes) };
-#elif
+#else
          return uuid{};
 #endif
       }