Merge pull request #5781 from ghalliday/issue10454

HPCC-10454 Fix build break in windows - missing _API specifier

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>

common/workunit/workunit.hpp

@@ -1354,6 +1354,6 @@ extern WORKUNIT_API void descheduleWorkunit(char const * wuid);
 void WORKUNIT_API testWorkflow();
 #endif
 
-const char * getWorkunitStateStr(WUState state);
+extern WORKUNIT_API const char * getWorkunitStateStr(WUState state);
 
 #endif