resolve comments and update code comment

Author: mingmingl-llvm

llvm/include/llvm/LTO/LTO.h

@@ -40,7 +40,6 @@ class MemoryBufferRef;
 class Module;
 class raw_pwrite_stream;
 class ToolOutputFile;
-class UniqueStringSaver;
 
 /// Resolve linkage for prevailing symbols in the \p Index. Linkage changes
 /// recorded in the index and the ThinLTO backends must apply the changes to

llvm/include/llvm/Support/Allocator.h

@@ -22,7 +22,6 @@
 #include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MathExtras.h"
-#include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>

llvm/lib/LTO/LTO.cpp

@@ -1812,7 +1812,7 @@ Error LTO::runThinLTO(AddStreamFn AddStream, FileCache Cache,
   // cross module importing, which adds to peak memory via the computed import
   // and export lists.
   GlobalResolutions.reset();
-  // Reset the bump pointer allocator to release its memory.
+  // Release the string saver memory.
   GlobalResolutionSymbolSaver.reset();
   Alloc.reset();