Win compile fix (#974)

lib/VCMIDirs.h

@@ -52,4 +52,5 @@ public:
 #endif
 	}
 };
-extern VCMIDirs GVCMIDirs;
+
+extern DLL_LINKAGE VCMIDirs GVCMIDirs;

lib/VCMI_Lib.cpp

@@ -32,7 +32,7 @@ DLL_LINKAGE CLodHandler *bitmaph = NULL,
 	*spriteh = NULL,
 	*bitmaph_ab = NULL;
 
-VCMIDirs GVCMIDirs;
+DLL_LINKAGE VCMIDirs GVCMIDirs;
 
 
 DLL_LINKAGE void initDLL(CConsoleHandler *Console, std::ostream *Logfile)