add builddate (if defined) to rc

src/version.h

@@ -8,5 +8,5 @@
 #define SUBMAJOR3PROXY 9
 #define MINOR3PROXY 2
 #define SUBMINOR3PROXY 0
-#define RELEASE3PROXY "3proxy-0.9.2\0"
+#define RELEASE3PROXY "3proxy-0.9.2(" BUILDDATE ")\0"
 #define YEAR3PROXY "2020"