PNaCl: Strip `nonnull` attributes from pointer arguments.

test/Transforms/NaCl/replace-ptrs-with-ints.ll

Index: test/Transforms/NaCl/replace-ptrs-with-ints.ll
diff --git a/test/Transforms/NaCl/replace-ptrs-with-ints.ll b/test/Transforms/NaCl/replace-ptrs-with-ints.ll
index aaba9da0b7dd9deffa2edc90e1fa09b1856b24e5..f53a4c4914ccdd36beb66992febd011a7407af44 100644
--- a/test/Transforms/NaCl/replace-ptrs-with-ints.ll
+++ b/test/Transforms/NaCl/replace-ptrs-with-ints.ll
@@ -490,6 +490,11 @@ define void @readonly_readnone(i8* readonly readnone) {
 }
 ; CHECK-LABEL: define void @readonly_readnone(i32)
 
+define void @nonnull_ptr(i8* nonnull) {
+  ret void
+}
+; CHECK-LABEL: define void @nonnull_ptr(i32)
+
 ; "nounwind" should be preserved.
 define void @nounwind_func_attr() nounwind {
   ret void