Clarify confusing GUID-length message

The GUID parameter to RetrieveSymbols must be exactly 32 characters in
length but when it isn't the tool wouldn't tell you what the length was.
It would also print some confusing information about trimmed GUIDs
which was not always relevant.

Now it prints the size and only prints the trimming information when it
is relevant (and more clearly).

RetrieveSymbols/RetrieveSymbols.cpp

@@ -122,9 +122,13 @@ int main(int argc, _Pre_readable_size_(argc) char* argv[])
      }
      if (gText.size() != 32)
      {
-         printf("Error: PDB GUIDs must be exactly 32 characters"
-                " (%s was stripped to %s).\n", gTextArg.c_str(), gText.c_str());
-         return 10;
+        if (gText == gTextArg)
+          printf("Error: PDB GUIDs must be exactly 32 characters, length of %s is %zu.",
+            gText.c_str(), gText.size());
+        else
+          printf("Error: PDB GUIDs must be exactly 32 characters, length of %s (stripped from %s) is %zu.",
+            gText.c_str(), gTextArg.c_str(), gText.size());
+        return 10;
      }
 
      int count = sscanf_s(gText.substr(0, 8).c_str(), "%x", &g.Data1);