[2831] Clarify comment about overflow

src/lib/util/memory_segment_mapped.h

@@ -183,7 +183,7 @@ public:
     ///
     /// This method goes over all pages of the underlying mapped memory
     /// segment, and returns the sum of the value of the first byte of each
-    /// page (ignoring any possible overflow).  It only proves weak integrity
+    /// page (wrapping around upon overflow).  It only proves weak integrity
     /// of the file contents, but can run fast enough and will ensure all
     /// pages are actually on memory.  The latter property will be useful
     /// if the application cannot allow the initial page fault overhead.