constant fold ptrtoint(inttoptr) with target data when available. This allows

constant fold ptrtoint(inttoptr) with target data when available.  This allows
us to fold the entry block of PR1602 to false instead of:

br i1 icmp eq (i32 and (i32 ptrtoint (void (%struct.S*)* inttoptr (i64
1 to void (%struct.S*)*) to i32), i32 1), i32 0), label %cond_next, label
%cond_true

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41023 91177308-0d34-0410-b5e6-96231b3b80d8