Merge pull request #3869 from ghalliday/issue8621

HPCC-8621 Reinstate typedef for hash64_t when compiling on windows

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

rtl/eclrtl/eclinclude.hpp

@@ -55,6 +55,7 @@ typedef unsigned short UChar;
 
 #ifdef _WIN32
 typedef unsigned int size32_t; // avoid pulling in platform.h (which pulls in windows.h etc) just for this...
+typedef unsigned __int64 hash64_t;
 #else
 #include "platform.h"
 #endif