[memprof] Fix typos in serializedSizeV0 and serializedSizeV2 (#88629)

The first field to serialize is the size of
IndexedMemProfRecord::AllocSites.  It has nothing to do with
GlobalValue::GUID.  This happens to work because of:

  using GUID = uint64_t;

Author: kazutakahirata

llvm/lib/ProfileData/MemProf.cpp

@@ -42,7 +42,8 @@ size_t IndexedAllocationInfo::serializedSize(IndexedVersion Version) const {
 }
 
 static size_t serializedSizeV0(const IndexedMemProfRecord &Record) {
-  size_t Result = sizeof(GlobalValue::GUID);
+  // The number of alloc sites to serialize.
+  size_t Result = sizeof(uint64_t);
   for (const IndexedAllocationInfo &N : Record.AllocSites)
     Result += N.serializedSize(Version0);
 
@@ -57,7 +58,8 @@ static size_t serializedSizeV0(const IndexedMemProfRecord &Record) {
 }
 
 static size_t serializedSizeV2(const IndexedMemProfRecord &Record) {
-  size_t Result = sizeof(GlobalValue::GUID);
+  // The number of alloc sites to serialize.
+  size_t Result = sizeof(uint64_t);
   for (const IndexedAllocationInfo &N : Record.AllocSites)
     Result += N.serializedSize(Version2);