Disallow implicit and explicit casts of vector types in llvm-rs-cc.

Bug: 7342914

Vector types are aggregates (just like structs), and casting of any type
results in bitcasts being generated. This misbehaves when converting between
things like float and int. Even more troublesome than explicit casts are
implicit casts, which can arise from accidental arithmetic operations between
two different vector types.

Change-Id: If27a0f70d1da5f1773261a38e6b4572aeb976701
5 files changed