[lldb] Don't report missing object files for shared cache images (#237298)
eb5f248268fb reports an error when a debug map object file does not
exist. Unstripped shared cache images have N_OSO entries that point at
object files from the OS build. Users have no control over these images,
so the error is noise they can't act on.
Skip the report for images with MH_DYLIB_IN_CACHE. LLDB still records
the error for "image dump separate-debug-info" and "frame variable".
Checking the install name instead would also silence locally built roots
at shared cache eligible paths. Those aren't in the cache, and their
owners can fix them.
rdar://189926934