Convert a few lit tests that use "lc2i | llvm-mc | llvm-objdump" to use p2i.

tests_lit/llvm2ice_tests/struct-arith.pnacl.ll

 ; This test is lowered from C code that does some simple aritmetic
 ; with struct members.
 
-; TODO(kschimpf) Find out why lc2i is needed.
-; REQUIRES: allow_llvm_ir_as_input
-; RUN: %lc2i -i %s --args --verbose inst -threads=0 | FileCheck %s
+; REQUIRES: allow_dump
+; RUN: %p2i -i %s --args --verbose inst -threads=0 | FileCheck %s
 
 define internal i32 @compute_important_function(i32 %v1, i32 %v2) {
 entry:
   %__2 = inttoptr i32 %v1 to i32*
   %_v0 = load i32* %__2, align 1
 
 ; CHECK:        entry:
-; CHECK-NEXT:       %__2 = i32 %v1
 ; CHECK-NEXT:       %_v0 = load i32* {{.*}}, align 1
 
   %__4 = inttoptr i32 %v2 to i32*
   %_v1 = load i32* %__4, align 1
   %gep = add i32 %v2, 12
   %__7 = inttoptr i32 %gep to i32*
   %_v2 = load i32* %__7, align 1
   %mul = mul i32 %_v2, %_v1
   %gep6 = add i32 %v1, 4
   %__11 = inttoptr i32 %gep6 to i32*
@@ skipping 16 matching lines @@
   %mul11 = mul i32 %mul9, %_v7
   %add4.neg = add i32 %mul, %_v0
   %add = sub i32 %add4.neg, %_v3
   %sub = sub i32 %add, %mul3
   %sub12 = sub i32 %sub, %mul11
   ret i32 %sub12
 
 ; CHECK:        %sub12 = sub i32 %sub, %mul11
 ; CHECK-NEXT:       ret i32 %sub12
 }