Adding WIN32 switch for DLL import/export definition

CMakeLists.txt

@@ -169,8 +169,11 @@ if( ITA_BASE_WITH_CONFIG_OLD_IMPL AND NOT ITA_BASE_WITH_CONFIG_SIMPLE_INI )
 	list( APPEND ITABaseSources "src/ITAConfigUtilsWin32Impl.cpp" )
 endif( ITA_BASE_WITH_CONFIG_OLD_IMPL AND NOT ITA_BASE_WITH_CONFIG_SIMPLE_INI )
 
-# compiler
-add_definitions( -DITA_BASE_DLL -DITA_BASE_EXPORT )
+
+# Windows DLL compiler flags
+if( WIN32 )
+	add_definitions( -DITA_BASE_DLL -DITA_BASE_EXPORT )
+endif( WIN32)
 
 
 # linker