[mips] Fix debug information for __thread variable

This patch fixes debug information for __thread variable on Mips
using .dtprelword and .dtpreldword directives.

Patch by Aleksandar Beserminji.

Differential Revision: http://reviews.llvm.org/D28770

llvm-svn: 292624
diff --git a/llvm/lib/Target/Mips/MipsTargetObjectFile.h b/llvm/lib/Target/Mips/MipsTargetObjectFile.h
index e5423f9..a37ec15 100644
--- a/llvm/lib/Target/Mips/MipsTargetObjectFile.h
+++ b/llvm/lib/Target/Mips/MipsTargetObjectFile.h
@@ -42,6 +42,8 @@
     MCSection *getSectionForConstant(const DataLayout &DL, SectionKind Kind,
                                      const Constant *C,
                                      unsigned &Align) const override;
+    /// Describe a TLS variable address within debug info.
+    const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const override;
   };
 } // end namespace llvm