Explain the Emacs Lisp predicate
[Fix #45] Work around package-install issues

Do not check syntax in temporary buffers created by `byte-compile-file`
and autoloads buffers used during `package-install` because these
interfere with byte compilation and autoloads generation during package
installation.  These buffers are created temporarily to hold input fed
to the byte compiler and to collect all autoloads of a package
respectively.  During `package-install` the checker will kick in and
attempt to check these buffers, but it will be interrupted early because
these buffers are very short-lived, causing pointless "kill buffer?"
questions and errors about deleted buffers.

For now, we simply check against the names of such buffers (which are
hard-coded in `bytecomp.el` and `package.el` anyway) because there is
apparently no other way to reliably identify such buffers.