Introduce f[no-]max-unknown-pointer-align=[number] option
to instruct the code generator to not enforce a higher alignment 
than the given number (of bytes) when accessing memory via an opaque 
pointer or reference. Patch reviewed by John McCall (with post-commit
review pending). rdar://16254558


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@214911 91177308-0d34-0410-b5e6-96231b3b80d8