[ELF2] Constify getStrTabSec().

llvm-svn: 248360
diff --git a/lld/ELF/OutputSections.h b/lld/ELF/OutputSections.h
index 9ecf363..38706b9 100644
--- a/lld/ELF/OutputSections.h
+++ b/lld/ELF/OutputSections.h
@@ -185,7 +185,7 @@
       ++NumLocals;
   }
 
-  StringTableSection<ELFT::Is64Bits> &getStrTabSec() { return StrTabSec; }
+  StringTableSection<ELFT::Is64Bits> &getStrTabSec() const { return StrTabSec; }
   unsigned getNumSymbols() const { return NumVisible + 1; }
   void setBssSec(const OutputSection<ELFT> *V) { BssSec = V; }