Cherry-pick r234714: [MC] Write padding into fragments when -mc-relax-all flag is used

include/llvm/MC/MCObjectStreamer.h

Index: include/llvm/MC/MCObjectStreamer.h
diff --git a/include/llvm/MC/MCObjectStreamer.h b/include/llvm/MC/MCObjectStreamer.h
index 0866ff5a9fc089020bce6633bdc08de0f9c65851..e581ec3a382f99a268fd31356ebde77dde1d31be 100644
--- a/include/llvm/MC/MCObjectStreamer.h
+++ b/include/llvm/MC/MCObjectStreamer.h
@@ -44,10 +44,6 @@ class MCObjectStreamer : public MCStreamer {
   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
 
-  // If any labels have been emitted but not assigned fragments, ensure that
-  // they get assigned, either to F if possible or to a new data fragment.
-  void flushPendingLabels(MCFragment *F);
-
 protected:
   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &_OS,
                    MCCodeEmitter *_Emitter);
@@ -85,6 +81,12 @@ protected:
   /// fragment is not a data fragment.
   MCDataFragment *getOrCreateDataFragment();
 
+  /// If any labels have been emitted but not assigned fragments, ensure that
+  /// they get assigned, either to F if possible or to a new data fragment.
+  /// Optionally, it is also possible to provide an offset \p FOffset, which
+  /// will be used as a symbol offset within the fragment.
+  void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
+
 public:
   void visitUsedSymbol(const MCSymbol &Sym) override;