Add missing const specifier to a const method.

llvm-svn: 210265
diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
index 43360d3..e8bdcce 100644
--- a/llvm/lib/IR/DebugLoc.cpp
+++ b/llvm/lib/IR/DebugLoc.cpp
@@ -76,7 +76,7 @@
   return getScope(Ctx);
 }
 
-DebugLoc DebugLoc::getFnDebugLoc(const LLVMContext &Ctx) {
+DebugLoc DebugLoc::getFnDebugLoc(const LLVMContext &Ctx) const {
   const MDNode *Scope = getScopeNode(Ctx);
   DISubprogram SP = getDISubprogram(Scope);
   if (SP.isSubprogram()) {