Correct for buffer local variables

Remove 'make-variable-buffer-local', because its usage is wrong and
'c-basic-offset' and 'c-offsets-alist' are already buffer-local
variables. And we should not use 'setq-default' because it effects
for other buffers.
Fix byte-compile warnings
Add autoload cookie for lazy loading
Fix calling function

Original code makes no sense and causes error.
Merge pull request #1 from syohex/fix-various-things

Fix various things