[analyzer] Teach RetainCountChecker about CVFooRetain

[analyzer] Teach RetainCountChecker about CVFooRetain

Change the retain count checker to treat CoreFoundation-style "CV"-prefixed
reference types from CoreVideo similarly to CoreGraphics types. With this
change, we treat CVFooRetain() on a CVFooRef type as a retain. CVFooRelease()
APIs are annotated as consuming their parameter, so this change prevents false
positives about incorrect decrements of reference counts.

<rdar://problem/27116090>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@278382 91177308-0d34-0410-b5e6-96231b3b80d8