[bolt] Don't call llvm::raw_string_ostream::flush() (NFC)

Don't call raw_string_ostream::flush(), which is essentially a no-op.
As specified in the docs, raw_string_ostream is always unbuffered.
( 65b1361 for further reference )

Author: JOE1994

bolt/include/bolt/Core/BinaryData.h

@@ -226,7 +226,6 @@ inline raw_ostream &operator<<(raw_ostream &OS,
     Sep = ",\n        ";
     TotalCount += AccessInfo.Count;
   }
-  SS.flush();
 
   OS << TotalCount << " total counts : " << TempString;
   return OS;

bolt/include/bolt/Core/BinaryFunction.h

@@ -117,7 +117,6 @@ inline raw_ostream &operator<<(raw_ostream &OS,
     TotalCount += CSP.Count;
     TotalMispreds += CSP.Mispreds;
   }
-  SS.flush();
 
   OS << TotalCount << " (" << TotalMispreds << " misses) :" << TempString;
   return OS;

bolt/lib/Passes/RetpolineInsertion.cpp

@@ -181,7 +181,6 @@ std::string createRetpolineFunctionTag(BinaryContext &BC,
   if (BrInfo.isReg()) {
     BC.InstPrinter->printRegName(TagOS, BrInfo.BranchReg);
     TagOS << "_";
-    TagOS.flush();
     return Tag;
   }
 
@@ -212,7 +211,6 @@ std::string createRetpolineFunctionTag(BinaryContext &BC,
     BC.InstPrinter->printRegName(TagOS, MemRef.SegRegNum);
   }
 
-  TagOS.flush();
   return Tag;
 }
 

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -4245,7 +4245,6 @@ void RewriteInstance::addBoltInfoSection() {
          << "command line:";
   for (int I = 0; I < Argc; ++I)
     DescOS << " " << Argv[I];
-  DescOS.flush();
 
   // Encode as GNU GOLD VERSION so it is easily printable by 'readelf -n'
   const std::string BoltInfo =
@@ -4268,7 +4267,6 @@ void RewriteInstance::encodeBATSection() {
   raw_string_ostream DescOS(DescStr);
 
   BAT->write(*BC, DescOS);
-  DescOS.flush();
 
   const std::string BoltInfo =
       BinarySection::encodeELFNote("BOLT", DescStr, BinarySection::NT_BOLT_BAT);

bolt/lib/RuntimeLibs/InstrumentationRuntimeLibrary.cpp

@@ -314,7 +314,6 @@ std::string InstrumentationRuntimeLibrary::buildTables(BinaryContext &BC) {
   }
   // Our string table lives immediately after descriptions vector
   OS << Summary->StringTable;
-  OS.flush();
 
   return TablesStr;
 }