Don't assert everytime an intrinsic name isn't recognized. Instead, make
the assert optional when callin getIntrinsicID(). This allows the assembler
to handle invalid intrinsic names gracefully.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36120 91177308-0d34-0410-b5e6-96231b3b80d8
