scripts: checkversion: modernize linux/version.h search strings

Update scripts/checkversion.pl to recognize the current contents
of <linux/version.h> and both of its current locations.

Also update my email address.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>