[SimplifyLibCalls] Add NoUndef/NonNull/Dereferenceable attributes to iprintf/siprintf

When SimplifyLibCalls fail to optimize printf and sprintf it add
NoUndef/NonNull/Dereferenceable attributes. This patch add the same attributes
if SimplifyLibCalls optimize printf/sprintf into the integer only
iprintf/siprintf.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D136140