PNaCl: Strip `nonnull` attributes from pointer arguments.

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

 ; RUN: opt %s -replace-ptrs-with-ints -S | FileCheck %s
 
 target datalayout = "p:32:32:32"
 
 
 %struct = type { i32, i32 }
 
 declare %struct* @addr_taken_func(%struct*)
 
 @addr_of_func = global %struct* (%struct*)* @addr_taken_func
@@ skipping 472 matching lines @@
   ret void
 }
 ; CHECK: define void @nocapture_attr(i32 %ptr) {
 
 
 define void @readonly_readnone(i8* readonly readnone) {
   ret void
 }
 ; 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
 }
 ; CHECK: define void @nounwind_func_attr() [[NOUNWIND:#[0-9]+]] {
 
 define void @nounwind_call_attr() {
   call void @nounwind_func_attr() nounwind
   ret void
 }
@@ skipping 122 matching lines @@
 !9 = metadata !{metadata !10}
 !10 = metadata !{metadata !"0x101\00ptr\0016777217\000", metadata !4, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [ptr] [line 1]
 !11 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
 !12 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
 !13 = metadata !{metadata !"clang version 3.6.0"}
 !14 = metadata !{metadata !"0x102"}               ; [ DW_TAG_expression ]
 !15 = metadata !{i32 1, i32 16, metadata !4, null}
 !16 = metadata !{i32 2, i32 1, metadata !4, null}
 
 ; CHECK: !4 = metadata !{{{.*}}nop{{.*}}, void (i32)* @nop, {{.*}}} ; [ DW_TAG_subprogram ] [line 1] [def] [nop]