Remove a couple of warnings.

Author: johnno1962

lld/MachO/Driver.cpp

@@ -311,17 +311,16 @@ void multiThreadedPageInBackground(const DeferredFiles &deferred) {
       totalBytes += buff.size();
 
       // Reference all file's mmap'd pages to load them into memory.
+      volatile char t = 0;
       for (const char *page = buff.data(), *end = page + buff.size();
            page < end; page += pageSize)
-        volatile char t = *page;
+        t += *page;
     }
   });
 
-#ifndef NDEBUG
   if (getenv("LLD_MULTI_THREAD_PAGE"))
     llvm::dbgs() << "multiThreadedPageIn " << totalBytes << "/"
                  << deferred.size() << "\n";
-#endif
 }
 
 static void multiThreadedPageIn(const DeferredFiles &deferred) {

lld/MachO/Options.td

@@ -397,7 +397,7 @@ def interposable : Flag<["-"], "interposable">,
     HelpText<"Indirects access to all exported symbols in an image">,
     Group<grp_opts>;
 def read_threads : Joined<["--"], "read-threads=">,
-    HelpText<"Number of threads to use to proactively page in files. 20 would be a typical value, use 0 to disable this feature.">,
+    HelpText<"Number of threads to use to proactively page in files for faster disk i/o. 20 would be a typical value, use 0 to disable this feature.">,
     Group<grp_lld>;
 def order_file : Separate<["-"], "order_file">,
     MetaVarName<"<file>">,