Support IRgen of sqrt -> llvm.sqrt, pow -> llvm.pow.

 - Define pow[lf]?, sqrt[lf]? as builtins.

 - Add -fmath-errno option which binds to LangOptions.MathErrno

 - Add new builtin flag Builtin::Context::isConstWithoutErrno for
   functions which can be marked as const if errno isn't respected for
   math functions. Sema automatically marks these functions as const
   when they are defined, if MathErrno=0.

 - IRgen uses const attribute on sqrt and pow library functions to
   decide if it can use the llvm intrinsic.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64689 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 5f42a42..7f36c71 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -631,7 +631,8 @@
                       CallExpr::const_arg_iterator ArgBeg,
                       CallExpr::const_arg_iterator ArgEnd);
 
-  RValue EmitBuiltinExpr(unsigned BuiltinID, const CallExpr *E);
+  RValue EmitBuiltinExpr(const FunctionDecl *FD, 
+                         unsigned BuiltinID, const CallExpr *E);
 
   RValue EmitBlockCallExpr(const CallExpr *E);