MachO: support N_INDR aliases in assembly files.

This makes LLVM create N_INDR aliases (to be resolved by the linker) when
appropriate.

rdar://problem/15125513

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209894 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCMachObjectWriter.h

@@ -111,6 +111,8 @@ class MachObjectWriter : public MCObjectWriter {
 
   /// @}
 
+  MachSymbolData *findSymbolData(const MCSymbol &Sym);
+
 public:
   MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS,
                    bool _IsLittleEndian)