implement support for __builtin_eh_return_data_regno on x86-32 and x86-64.
This implements PR5034 and rdar://6836445.

llvm-svn: 82614
diff --git a/clang/test/Sema/builtins.c b/clang/test/Sema/builtins.c
index c3daa66..04a56bd 100644
--- a/clang/test/Sema/builtins.c
+++ b/clang/test/Sema/builtins.c
@@ -52,3 +52,13 @@
  
   // No warning about falling off the end of a noreturn function.
 }
+
+void test11(int X) {
+  switch (X) {  
+  case __builtin_eh_return_data_regno(0):  // constant foldable.
+    break;
+  }
+
+  __builtin_eh_return_data_regno(X);  // expected-error {{not an integer constant expression}}
+}
+