Compile Bolt using std 14.

Summary:
Compile Bolt using std 14.
We want that to be able to use some threading the locking tools that do not exists in std 11.

(cherry picked from FBD15671736)

bolt/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(BOLT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(BOLT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+set(CMAKE_CXX_STANDARD 14)
 
 add_subdirectory(src)
 add_subdirectory(test)

bolt/src/DataReader.cpp

@@ -267,7 +267,7 @@ DataReader::readPerfData(StringRef Path, raw_ostream &Diag) {
     Diag << "cannot open " << Path << ": " << EC.message() << "\n";
     return EC;
   }
-  auto DR = make_unique<DataReader>(std::move(MB.get()), Diag);
+  auto DR = llvm::make_unique<DataReader>(std::move(MB.get()), Diag);
   if (auto EC = DR->parse()) {
     return EC;
   }

bolt/src/ProfileWriter.cpp

@@ -161,7 +161,7 @@ ProfileWriter::writeProfile(const RewriteInstance &RI) {
   const auto &Functions = RI.getBinaryContext().getBinaryFunctions();
 
   std::error_code EC;
-  OS = make_unique<raw_fd_ostream>(FileName, EC, sys::fs::F_None);
+  OS = llvm::make_unique<raw_fd_ostream>(FileName, EC, sys::fs::F_None);
   if (EC) {
     errs() << "BOLT-WARNING: " << EC.message() << " : unable to open "
            << FileName << " for output.\n";