[memprof] Use a lambda instead of std::bind (NFC) (#144940)

A lambda is a lot shorter than std::bind here.

Author: kazutakahirata

llvm/include/llvm/ProfileData/MemProfReader.h

@@ -62,8 +62,7 @@ class MemProfReader {
       return make_error<InstrProfError>(instrprof_error::eof);
 
     if (Callback == nullptr)
-      Callback =
-          std::bind(&MemProfReader::idToFrame, this, std::placeholders::_1);
+      Callback = [&](FrameId Id) { return idToFrame(Id); };
 
     CallStackIdConverter<decltype(MemProfData.CallStacks)> CSIdConv(
         MemProfData.CallStacks, Callback);