[GCC] Attribute ifunc support in clang

This patch add support for GCC attribute((ifunc("resolver"))) for
targets that use ELF as object file format. In general ifunc is a
special kind of function alias with type @gnu_indirect_function. LLVM
patch http://reviews.llvm.org/D15525

Differential Revision: http://reviews.llvm.org/D15524

llvm-svn: 265917
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index f76f0ba..e1b4ef9 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1175,6 +1175,7 @@
   void EmitGlobalFunctionDefinition(GlobalDecl GD, llvm::GlobalValue *GV);
   void EmitGlobalVarDefinition(const VarDecl *D, bool IsTentative = false);
   void EmitAliasDefinition(GlobalDecl GD);
+  void emitIFuncDefinition(GlobalDecl GD);
   void EmitObjCPropertyImplementations(const ObjCImplementationDecl *D);
   void EmitObjCIvarInitializations(ObjCImplementationDecl *D);