[llvm-profdata][NFC] fix warning

[liaolucy]

Summary

warning: unused variable ‘FC’

[kazu]

Thanks! Just for my own education, which compiler did you use to build llvm?

[liaolucy]

In D132429#3741431, @kazu wrote:

Thanks! Just for my own education, which compiler did you use to build llvm?

Sorry, I can't remember exactly, it's probably clang. (It was configured a long time ago.)

cmake add -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++

llvm/lib/ProfileData/SampleProfReader.cpp

 }
 
 /// Dump all the function profiles found on stream \p OS in the JSON format.
 void SampleProfileReader::dumpJson(raw_ostream &OS) {
   std::vector<NameFunctionSamples> V;
   sortFuncProfiles(Profiles, V);
   json::OStream JOS(OS, 2);
   JOS.arrayBegin();
-  for (const auto &[FC, FS] : V)
-    dumpFunctionProfileJson(*FS, JOS, true);
+  for (const auto &F : V)
+    dumpFunctionProfileJson(*F.second, JOS, true);
   JOS.arrayEnd();
 
   // Emit a newline character at the end as json::OStream doesn't emit one.
   OS << "\n";
 }
 
 /// Parse \p Input as function head.
 ///